,transcriber's ,note3 ,italic text is denoted by underscores and bold text by tildes4 ,superscripted text is enclosed in braces and preceded by a caret 774 ,,cambridge ,,agricultural ,,monographs ,,inorganic ,,plant ,,poisons ,,and ,,stimulants ,,cambridge ,,university ,,press ,c4 ,f4 ,,clay1 ,,manager ,london3 ,,fetter ,,lane1 ,e4,c4 ,edinburgh3 #ajj ,,princes ,,street ,colophon ,london3 ,h4 ,k4 ,,lewis1 #acf ,,gower ,,street1 ,w4,c4 ,london3 ,,william ,,wesley ,,and ,,son1 #bh ,,essex ,,street1 ,,strand ,new ,york3 ,g4 ,p4 ,,putnam',s ,,sons ,bombay and ,calcutta3 ,,macmillan ,,and ,,co41 ,,ltd4 ,toronto3 ,j4 ,m4 ,,dent ,,and ,,sons1 ,,ltd4 ,tokyo3 ,,the ,,maruzen-,,kabushiki-,,kaisha ,all rights reserved ,,inorganic ,,plant ,,poisons ,,and ,,stimulants ,,by ,,winifred ,e4 ,,brenchley1 ,d4,,sc41 ,f4,l4,s4 ,fellow of ,university ,college1 ,london 7,rothamsted ,experimental ,station7 ,cambridge3 at the ,university ,press #aiad ,cambridge3 ,,printed ,,by ,,john ,,clay1 ,m4,a4 ,,at ,,the ,,university ,,press ,,preface ,during the last century great and widespread changes have been made in agricultural practice--changes largely associated with the increase in the use of artificial fertilisers as supplements to the bulky organic manures which had hitherto been used4 ,the value of certain chemical compounds as artificial manures is fully recognised1 yet many attempts are being made to prove the value of other substances for the same purpose1 with a view to increase in efficiency and decrease in cost4 ,the interest in the matter is naturally great1 and agriculturists1 botanists and chemists have all approached the question from their different standpoints4 ,in the following pages an attempt is made to correlate the work that has been done on a few inorganic substances which gave promise of proving useful in agricultural practice4 ,much of the evidence put forward by different workers is conflicting1 and it is clear that no definite conclusions can yet be reached4 ,nevertheless1 examination of the evidence justifies the hope that results of practical value will yet be obtained1 and it is hoped that the analysis and coordination of the available data put forward in this book will aid in clearing the ground for those investigators who are following up the problem from both the academic and the practical standpoints4 ,w4 ,e4 ,b4 ,,rothamsted4 ,october #aiad4 ,,contents ,,chap4 ,,page ,i4 ,,introduction #a ,,ii4 ,,methods ,,of ,,working #g ,i4 ,discussion of ,methods #g #a4 ,water cultures #g #b4 ,sand cultures #h #c4 ,soil cultures in pots #i #d4 ,field experiments #i ,,ii4 ,details of ,methods #aj ,,iii4 ,,effect ,,of ,,copper ,,compounds #ae ,i4 ,presence of ,copper in ,plants #ae ,,ii4 ,effect of ,copper on the ,growth of ,higher ,plants #ag #a4 ,toxic effect #ag 7a7 ,toxic action of copper compounds alone in water cultures #ag 7b7 ,masking effect caused by addition of soluble substances to solutions of copper salts #bj 7c7 ,effect of adding insoluble substances to solutions of copper salts #bb 7d7 ,effect of copper on plant growth when present in soils #bd 7e7 ,mode of action of copper on plants #be #b4 ,effect of copper on germination #bg 7a7 ,seeds #bg 7b7 ,spores and pollen grains #bh #c4 ,does copper stimulate higher plants8 #bh #d4 ,action of copper on organs other than roots #cj 7a7 ,effect of copper sprays on leaves #cj 7b7 ,effect of solutions of copper salts on leaves #cb ,,iii4 ,effect of ,copper on ,certain of the ,lower ,plants #cc ,conclusion #ce ,,iv4 ,,effect ,,of ,,zinc ,,compounds #cf ,i4 ,presence of ,zinc in ,plants #cf ,,ii4 ,effect of ,zinc on the ,growth of ,higher ,plants #ch #a4 ,toxic effect #ch 7a7 ,toxic action of zinc salts alone in water cultures #ch 7b7 ,effect of soluble zinc salts in the presence of nutrients #ci 7c7 ,effect of zinc compounds on plant growth when they are present in soils #da 7d7 ,mode of action of zinc on plants #dc #b4 ,effect of zinc compounds on germination #dc #c4 ,stimulation induced by zinc compounds #de 7a7 ,stimulation in water cultures #de 7b7 ,stimulation in sand cultures #df 7c7 ,increased growth in soil #df #d4 ,direct action of zinc salts on leaves #dg ,,iii4 ,effect of ,zinc on ,certain of the ,lower ,plants #dh ,conclusion #ej ,v4 ,,effect ,,of ,,arsenic ,,compounds #ea ,i4 ,presence of ,arsenic in ,plants #ea ,,ii4 ,effect of ,arsenic on the ,growth of ,higher ,plants #eb #a4 ,toxic effect #eb 7a7 ,toxic action of arsenic compounds in water cultures in the presence of nutrients #eb 7b7 ,toxic effect of arsenic compounds in sand cultures #eg 7c7 ,toxic effect of arsenic when applied to soil cultures #eg 7d7 ,physiological considerations #ei #b4 ,effect of arsenic compounds on germination #fj #c4 ,do arsenic compounds stimulate higher plants8 #fa ,,iii4 ,effect of ,arsenic ,compounds on ,certain of the ,lower ,plants #fb #a4 ,algae #fb #b4 ,fungi #fc ,conclusion #fd ,,vi4 ,,effect ,,of ,,boron ,,compounds #fe ,i4 ,presence of ,boron in ,plants #fe ,,ii4 ,effect of ,boron on the ,growth of ,higher ,plants #fg #a4 ,toxic effect #fg 7a7 ,toxic action of boron compounds in water cultures #fg 7b7 ,toxic action of boron compounds in sand cultures #gj 7c7 ,toxic action of boron compounds in soil experiments #ga #b4 ,effect of boron compounds on germination #gb #c4 ,does boron stimulate higher plants8 #gc 7a7 ,water cultures #gc 7b7 ,sand cultures #gc 7c7 ,soil cultures #gd ,,iii4 ,effect of ,boron ,compounds on ,certain of the ,lower ,plants #gf ,conclusion #gg ,,vii4 ,,effect ,,of ,,manganese ,,compounds #gh ,i4 ,presence of ,manganese in ,plants #gh ,,ii4 ,effect of ,manganese on the ,growth of ,higher ,plants #ha #a4 ,toxic effect #ha 7a7 ,toxic action of manganese compounds in the presence of soluble nutrients #ha 7b7 ,toxic action of manganese compounds in sand cultures #hb 7c7 ,toxic action of manganese compounds in soil cultures #hb #b4 ,effect of manganese compounds on germination #hd #c4 ,does manganese stimulate higher plants8 #hd 7a7 ,stimulation in water cultures #he 7b7 ,stimulation in soil cultures #hf ,,iii4 ,effect of ,manganese ,compounds on ,certain of the ,lower ,plants #ij ,,iv4 ,physiological ,considerations of ,manganese ,stimulation #ij ,conclusion #ib ,,viii4 ,,conclusions #ic ,,bibliography #ig ,,index ,,of ,,plant-,,names #ajg ,,general ,,index #aji ,,list ,,of ,,illustrations x ,,list ,,of ,,illustrations ,,fig4 ,,page #a4 ,sketch illustrating water culture methods #ab #b4 ,photograph4 ,barley grown with copper sulphate ,to face #bj #c4 ,curve4 ,ditto #ba #d4 ,photograph4 ,peas grown with copper sulphate ,to face #bi #e4 ,curve4 ,ditto #bi #f4 ,curve4 ,barley grown with zinc sulphate #dj #g4 ,photograph4 ,peas grown with zinc sulphate ,to face #dj #h4 ,curve4 ,ditto #da #i4 ,photograph4 ,barley grown with arsenious acid ,to face #ed #aj4 ,curve4 ,ditto #ee #aa4 ,curve4 ,peas grown with arsenious acid #ee #ab4 ,curve4 ,barley grown with arsenic acid #ef #ac4 ,curve4 ,barley grown with sodium arsenite #ef #ad4 ,curve4 ,peas grown with sodium arsenite #eg #ae4 ,curve4 ,barley grown with boric acid #fi #af4 ,photograph4 ,peas grown with boric acid ,to face #fi #ag4 ,curve4 ,barley grown with manganese sulphate #he #ah4 ,photograph4 ,ditto ,to face #hf #ai4 ,photograph4 ,peas grown with manganese sulphate #hf ,,chapter ,i ,,introduction ,ever since the physiological side of botany began to emerge from obscurity1 the question of the relation between the nutrition and the growth of the plant has occupied a foremost position4 ,all kinds of theories1 both probable and improbable1 have been held as to the way in which plants obtain the various components of their foods4 ,but quite early in the history of the subject it was acknowledged that the soil was the source of the mineral constituents of the plant food1 and that the roots were the organs by which they were received into the plant4 ,a new chapter in the history of science was begun when ,liebig in #ahdj first discussed the importance of inorganic or mineral substances in plant nutrition4 ,this discussion led to a vast amount of work dealing with the problem of nutrition from many points of view1 and the general result has been the sorting out of the elements into three groups1 nutritive1 indifferent1 and toxic4 ,thus calcium1 phosphorus1 nitrogen and potassium are classed as nutritive1 arsenic1 copper and boron as toxic1 and many others are regarded as indifferent4 ,closer examination1 however1 shows that this division into three classes is too rigid4 ,now that experiments are more refined it has become evident that no such simple grouping is possible4 ,it has been found that typical nutrient salts are toxic when they are applied singly to the plant in certain concentrations1 the toxic power decreasing and the nutritive function coming into play more fully on the addition of other nutrient salts4 ,for instance1 ,burlingham found that the typical nutrient magnesium sulphate in concentrations above m_/#haib 7m molecular weight7 is toxic to most seedlings1 the degree of toxicity varying with the type of seedling and the conditions under which growth takes place4 ,it will be shown in the following pages that even such a typical poison as boric acid may1 under suitable conditions1 increase plant growth just as if it were a nutrient4 ,a review of the whole subject leads one to conclude that in general both favourable and unfavourable conditions of nutrition are present side by side1 and only when a balance is struck in favour of the good conditions can satisfactory growth take place4 ,as indicated above1 experiments have shown that the very substances that are essential for plant food may be1 in reality1 poisonous in their action1 exercising a decidedly depressing or toxic influence on the plant when they are presented singly to the roots4 ,this toxic action of food salts is decreased when they are mixed together1 so that the addition of one toxic food solution to another produces a mixture which is less toxic than either of its constituents4 ,consequently a balanced solution can be made in which the toxic effects of the various foods for a particular plant are reduced to a minimum1 enabling optimum growth to take place4 ,such a mixture of plant foods occurs in the soil1 the composition of course varying with the soil4 ,while the earliest observations set forth the poisonous action of various substances upon plants1 it was not long before investigators found that under certain conditions these very substances seemed to exert a beneficial rather than an injurious action4 ,the poisons were therefore said to act as 8stimulants0 when they were presented to the plant in sufficiently great dilution4 ,this stimulation was noticed with various plants and with several poisons1 and a hypothesis was brought forward that attempted to reconcile the new facts with the old conceptions4 ,any poison1 it was suggested1 might act as a stimulant1 if given in sufficiently small doses4 ,it will be seen in the following pages that this is not universally true1 such substances as copper1 zinc1 and arsenic failing to stimulate certain plants even in the most minute quantities so far tested4 ,of recent years investigators in animal physiology have brought into prominence the striking effect of minute quantities of certain substances in animal nutrition1 as for example iodine in the thyroid gland 7see ,e4 ,baumann1 #ahie74 ,this and other work has rendered it imperative to re-examine the parallel problems in plant physiology4 ,the words 8stimulant0 and 8stimulation0 themselves need more precise definition4 ,as a matter of fact the 8stimulation0 noticed by one observer is not necessarily held to be such by another4 ,stimulation may express itself in various ways--the green weight and the general appearance of the fresh plant may be improved1 the dry weight may be increased1 the transpiration current may be hurried up1 entailing increased absorption of water and food substances by the roots1 assimilation processes may be encouraged4 ,but these benefits are not of necessity correlated with one another1 e4g4 a plant treated with a dilute solution of poison may look much healthier and weigh far more in the green state than an untreated plant1 whereas the latter may prove the heavier in the dry state4 ,to a market gardener to whom size and appearance is so important1 stimulation means an improvement in his cabbages and lettuces in the green state1 even though the increased weight is chiefly due to additional water absorbed under the encouragement of the stimulative agent1 whereas to a scientific observer1 the dry weight may give a more accurate estimate of stimulation in that it expresses more fully an increased activity in the vital functions of the plant whereby the nutritive and assimilative processes have gone on more rapidly1 with a consequent increase in the deposition of tissue4 ,while stimulation expresses itself in the ways detailed above poisoning action also makes itself visible to the eye4 ,badly poisoned plants either fail to grow at all or else make very little or weak growth4 ,even when less badly affected the toxic action is well shown in some cases by the flaccidity of the roots1 and in others by the formation of a 8strangulation0 near the crown of the root1 which spreads to the stem1 making it into a thin thread1 while the leaves usually wither and die4 ,if such plants as peas are able to make any shoot growth at all the roots show signs of a desperate attempt to put forth laterals4 ,the primary root gets much thickened and then bursts down four sides1 the tips of the laterals all trying to force their way through in a bunch1 but failing to do so on coming in contact with the poison4 ,most curious malformations of the root arise from this strong effort of the plant to fight against adverse circumstances4 ,while all the inorganic substances examined in this monograph are toxic in high concentrations1 some lead to increased growth in lower concentrations1 while others apparently have no effect4 ,in this sense all substances could be classed as toxins1 even the nutrients4 ,thus the old distinction between toxin and nutrient has now lost its sharpness1 but it does not lose all its significance4 ,the old 8nutrients0 had certain definite characters in common1 in that they were essential to plant growth1 the growth being in a great degree proportional to the supply1 a relatively large amount of the nutrients being not only tolerated but necessary4 ,the substances dealt with more particularly in this book have none of these characters4 ,even those that cause increased growth do not appear to be essential1 at any rate not in the quantities that potassium1 phosphorus1 nitrogen1 c41 are essential1 while there is no evidence that growth is proportional to supply4 ,the substances fall into two groups3 7#a7 ,those that apparently become indifferent in high dilutions and never produce any increase in plant growth4 7#b7 ,those that cause a small1 but quite distinct1 increased growth when applied in quantities sufficiently small4 ,the former group may be legitimately regarded as toxins2 the latter present more difficulty and even now their function is not settled4 ,it is not clear whether they stimulate the protoplasm or in some way hasten the metabolic processes in the plant1 whether they help the roots in their absorbent work1 or whether they are simple nutrients needed only in infinitesimal quantities4 ,the two groups1 however1 cannot be sharply separated from one another4 ,indeed a substance may be put into one of these classes on the basis of experiments made with one plant alone and into another when a different plant is used1 while it is quite conceivable that further experiments with other plants may abolish the division between the two groups altogether4 ,it is even impossible to speak rigidly of toxicity4 ,the addition of the inorganic food salts to solutions of a poison reduces the toxicity of the latter1 so that the plant makes good growth in the presence of far more poison than it can withstand in the absence of the nutrients4 ,this masking effect of the inorganic food salts upon the toxicity of inorganic plant poisons is paralleled by a similar action on organic toxic agents4 ,schreiner and ,reed 7#aijh7 found that the addition of a second solute to a solution decreases the toxicity of that solution2 further the plant itself may exercise a modifying influence upon the toxic agent4 ,water culture experiments were made upon the toxicity of certain organic compounds1 with and without the addition of other inorganic salts4 ,arbutin1 vanillin1 and cumarin were definitely toxic and the toxicity decidedly fell off after the addition of sodium nitrate and calcium carbonate1 especially with the weaker solutions of the toxins4 ,curiously enough1 while weaker solutions of vanillin alone produced stimulation1 the stimulating effect of this toxic agent disappeared entirely on the addition of the inorganic substances4 ,the results showed that the addition of certain inorganic salts to solutions of toxic organic compounds was decidedly beneficial to the plant4 ,another important problem has come to the front with regard to these toxic substances--,how do these substances get into the plant8 ,are they all absorbed if they occur in the soil1 or is there any discriminatory power on the part of the root8 ,in other words1 do the roots perforce take in everything that is presented to their surfaces1 or have they the power of making a selection1 absorbing the useful and rejecting the useless and harmful8 ,daubeny 7#ahcc7 described experiments in which various plants1 as radish1 cabbage1 ,vicia ,faba1 hemp and barley were grown actually on sulphate of strontium or on soils watered with nitrate of strontium4 ,no strontium could be detected in the ash of any of the plants save barley1 and then only the merest trace was found4 ,daubeny concluded that the roots were able to reject strontium even when presented in the form of a solution4 8,upon the whole1 then1 ,i see nothing1 so far as experiments have yet gone1 to invalidate the conclusion 444 that the roots of plants do1 to a certain extent at least1 possess a power of selection1 and that the earthy constituents which form the basis of their solid parts are determined as to quality by some primary law of nature1 although their amount may depend upon the more or less abundant supply of the principles presented to them from without40 ,some years after1 in #ahfb1 ,daubeny reverted to the idea1 stating 8,i should be inclined to infer that the spongioles of the roots have residing in them some specific power of excluding those constituents of the soil that are abnormal and1 therefore1 unsuitable to the plant1 but that they take up those which are normal in any proportions in which they may chance to present themselves#a40 ,this1 however1 was not held to apply to such corrosive substances as copper sulphate4 ,de ,saussure had found that ,polygonum ,persecaria took up copper sulphate in large quantities1 a circumstance which he attributed to the poisonous and corrosive quality of this substance1 owing to which the texture of the cells became disorganised and the entrance of the solution into the vegetable texture took place as freely1 perhaps1 as if the plants had been actually severed asunder#b4 ,daubeny concluded that a plant is unable to exclude poisons of a corrosive nature1 as this quality of the substance destroys the vitality of the absorbing surface of the roots and thus reduces it to the condition of a simple membrane which by endosmosis absorbs whatever is presented to its external surfaces1 so that whenever abnormal substances are taken up by a living plant it is in consequence of some interference with the vital functions of the roots caused in the first instance by the deleterious influence of the agent employed4 #a ,this idea of a selectivity of the roots has been recently revived by ,colin and ,lavison 7#aiaj7 who found that when peas were grown in the presence of barium1 strontium or calcium salts no trace of barium could be found in the stem1 strontium only occurred in small quantities1 while calcium was present in abundance4 ,they concluded that apparently salts of the two latter alkaline metals could be absorbed by the roots and transferred to the stem and other organs1 but that this is not the case with salts of barium4 ,they obtained similar results with other plants1 beans1 lentils1 lupins1 maize1 wheat1 hyacinth4 ,their proof is not rigid1 and exception could be taken to it on chemical grounds4 #b ,vide ,daubeny1 ,journ4 ,chem4 ,soc4 7#ahfb71 p4 #baj4 ,in spite of the enormous amount of work that has been done on this subject of toxic action and stimulation it is yet too early to discuss the matter in any real detail4 ,a voluminous literature has arisen around the subject1 and in the present discussion some selection has been made with a view to presenting ascertained facts as succinctly as possible4 ,no attempt has been made to notice all the papers2 many have been omitted perforce2 it would have been impossible to deal with the matter within reasonable length otherwise4 ,a full and complete account would have demanded a ponderous treatise4 ,this widespread interest on the part of investigators is fully justified1 as the problems under discussion are not only of the highest possible interest to the plant physiologist1 but hold out considerable promise for the practical agriculturist4 ,,chapter ,,ii ,,methods ,,of ,,working ,i4 ,,discussion ,,of ,,methods4 ,in the course of the scattered investigations on plant poisons and stimulants1 various experimental methods have been brought into use1 but these all fall into the two main categories of water and soil cultures1 with the exception of a few sand cultures which hold a kind of intermediate position1 combining certain characteristics of each of the main groups4 ,the conditions of plant life appertaining to soil and water cultures are totally different1 so different that it is impossible to assume that a result obtained by one of the experimental methods must of necessity hold good in respect of the other method4 ,a certain similarity does exist1 and where parallel investigations have been carried out this becomes evident1 but it seems to be more or less individual1 the plant1 the poison and the cultural conditions each playing a part in determining the matter4 #a4 ,water cultures4 ,this method of cultivation represents the simplest type of experiment4 ,its great advantage is that the investigator has absolute control over all the experimental conditions4 ,nutritive salts and toxic substances can be supplied in exact quantities and do not suffer loss or change by interaction with other substances which are beyond control4 ,any precipitates which may form in the food solution are contained within the culture vessel and are available for use if needed4 ,the results are thus most useful as aids in interpreting the meaning of those from the field experiments1 the results of the one method frequently dovetailing in with those of the other in a remarkable way4 ,the disadvantage of the water culture method is that it is more or less unnatural1 as the roots of the plants are grown in a medium quite unlike that which they meet in nature1 a liquid medium replacing the solid one1 so that the roots have free access to every part of the substratum without meeting any opposition to their spread until the walls of the culture vessel are reached4 ,the conditions of aeration are also different1 for while the plant roots meet with gaseous air in the interstices of the soil1 in water cultures they are dependent upon the air dissolved in the solution1 so that respiration takes place under unusual conditions4 ,it is possible that the poverty of the air supply can be overcome by regular aeration of the solution1 resulting in decided improvement in growth1 as ,l4 ,m4 ,underwood 7#aiac7 has shown in recent work on barley in which continued aeration was carried out4 #b4 ,sand cultures4 ,this method has the advantage over water cultures in that the environment of the plant roots is somewhat more natural1 but on the other hand the work is cumbersome and costly1 while the conditions of nutrition1 watering1 c41 are less under control than in the water cultures4 ,sand cultures represent an attempt to combine the advantages of both soil and water cultures1 without their respective disadvantages4 ,generally speaking perfectly clean sand is used varying in coarseness in different tests1 and this is impregnated with nutritive solutions suitable for plant growth4 ,the sand is practically insoluble and sets up no chemical interaction with the nutritive compounds1 while it provides a medium for the growth of the plant roots which approximates somewhat to a natural soil4 ,it is probable1 however1 that a certain amount of adsorption or withdrawal from solution occurs1 whereby a certain proportion of the food salts are affiliated1 so to speak1 to the sand particles and are so held that they are removed from the nutritive solution in the interspaces and are not available for plant food1 the nutritive solution being thus weakened4 ,the same remark applies to the poisons that are added1 so that the concentration of the toxic substance used in the experiment does not necessarily indicate the concentration in which it is presented to the plant roots4 ,on the other hand1 undue concentration of the solution is apt to occur on account of the excessive evaporation from the surface of the sand4 ,the sand particles are relatively so coarse in comparison with soil particles that the water is held loosely and so is easily lost by evaporation1 thus concentrating the solution at the surface1 a condition that does not apply in soil work4 ,with care this disadvantage is easily overcome as it is possible to weigh the pots regularly and to make up the evaporation loss by the addition of water4 #c4 ,soil cultures in pots4 ,in this case the conditions of life are still more natural1 as the plant roots find themselves in their normal medium of soil4 ,but the investigator has now far less control1 and bacterial and other actions come into play1 while the nutrients and poisons supplied may set up interactions with the soil which it is impossible to fathom4 ,this method is useful in the laboratory as it is more convenient for handling and gives more exact quantitative results than plot experiments4 ,also the pots can be protected from many of the untoward experiences that are likely to befall the crops in the open field4 ,the conditions are somewhat more artificial1 as the root systems are confined and the drainage is not natural1 but on the whole the results of pot experiments are very closely allied to those obtained in the field by similar tests4 #d4 ,field experiments4 ,these make a direct appeal to the practical man1 but of the scientific methods employed the field experiments are the least under control4 ,the plants are grown under the most natural conditions of cultivation it is possible to obtain1 and for that reason much value has been attached to such tests4 ,certainly1 so far as the final practical application is concerned1 open field experiments are the only ones which give information of the kind required4 ,but from the scientific point of view one very great drawback exists in the lack of control that the investigator has over the conditions of experiment4 ,the seeds1 application of poison1 c41 can all be regulated to a nicety1 but the constitution of the soil itself and the soil conditions of moisture1 temperature and aeration introduce factors which are highly variable4 ,no one can have any idea of the composition of the soil even in a single field1 as it may vary1 sometimes very considerably1 at every step4 ,further1 no one knows the complicated action that may or may not occur in the soil on the addition of extraneous substances such as manures or poisons4 ,altogether1 one is working quite in the dark as to knowledge of what is going on round the plant roots4 ,it is impossible to attribute the results obtained to the direct action of the poison applied4 ,while the influence may be direct1 it may also happen that certain chemical and physical interactions of soil and poison occur1 and that the action on the plant is secondary and not primary1 so that a deleterious or beneficial result is not necessarily due to the action of the toxic or stimulating substance directly on the plant1 but it may be an indirect effect induced possibly by an increase or decrease in the available plant food1 or to some other physiological factor4 ,consequently great care is needed in interpreting the results of field experiments without the due consideration of those obtained by other methods4 ,,ii4 ,,details ,,of ,,methods4 ,many details of the sand and soil culture methods have been published by various investigators1 e4g4 ,hiltner gives accounts of sand cultures1 while the various publications issued from ,rothamsted deal largely with the soil experiments4 ,as this is the case1 and as all crucial experiments have always been and must always be done in water cultures1 it is only necessary to give here full details of these4 ,the great essential for success in water culture work is strict attention to detail4 ,cleanliness of apparatus and purity of reagents are absolutely indispensable1 as the failure of a set of cultures can often be traced to a slight irregularity in one of these two directions4 ,purity of distilled water is perhaps the greatest essential of all4 ,plant roots are extraordinarily sensitive to the presence of small traces of deleterious matter in the distilled water1 especially when they are grown in the absence of food salts4 ,ordinary commercial distilled water is generally useless as the steam frequently passes through tubes and chambers which get incrusted with various impurities1 metallic and otherwise1 of which slight traces get into the distilled water4 ,loew 7#ahia7 showed that water which contained slight traces of copper1 lead or zinc derived from distilling apparatus exercised a toxic influence which was not evident in glass distilled water4 ,this poisonous effect was removed by filtering through carbon dust or flowers of sulphur4 ,apparently only about the first #be litres of distilled water were toxic1 in the later distillate the deleterious substance was not evident4 ,the best water to use is that distilled in a jena glass still1 the steam being passed through a jena glass condenser4 ,for work on a large scale1 however1 it is impossible to get a sufficient supply of such water1 while the danger of breakage is very great4 ,experiments at ,rothamsted were made to find a metallic still that would supply pure water4 ,while silver salts are very injurious to plant growth it was found that water that had been in contact with pure metallic silver had no harmful action4 ,consequently a still was constructed in which the cooling dome and the gutters were made of pure silver without any alloy1 so placed that the steam impinged upon the silver dome1 condensed into the silver gutter and was carried off by a glass tube into the receptacle4 ,such water proved perfectly satisfactory so long as any necessary repairs to the still were made with pure silver1 but a toxic action set in directly ordinary solder was employed4 ,more recently a new tinned copper still has been employed with good results1 but this is somewhat dangerous for general purposes1 as in the event of the tin wearing off in any place1 copper poisoning sets in at once4 ,the water is always filtered through a good layer of charcoal as a final precaution against impurity4 ,in the ,rothamsted experiments no attempt is made to carry on the cultures under sterile conditions4 ,bottles of #fjj c4c4 capacity are used1 after being thoroughly cleaned by prolonged boiling 7about four hours7 followed by washing and rinsing4 ,the bottles are filled with nutritive solution and the appropriate dose of poison1 carefully labelled and covered with thick brown paper coats to exclude the light from the roots and to prevent the growth of unicellular green algae4 ,the corks to fit the bottles are either used brand new or1 if old1 are sterilised in the autoclave to avoid any germ contamination from previous experiments4 ,lack of care in this respect leads to diseased conditions due to the growth of fungi and harmful bacteria4 ,two holes are bored in each cork1 one to admit air1 the other to hold the plant1 and the cork is cut into two pieces through the latter hole4 ,the seeds of the experimental plants are 8graded10 weighed so that they only vary within certain limits1 e4g4 barley may be #je-jf gm41 peas #c-ce gm41 buckwheat #jb-jc gm4 ,in this way a more uniform crop is obtained4 ,great care is needed in selecting the seeds1 the purest strain possible being obtained in each case4 ,with barley it has always proved possible to get a pure pedigree strain1 originally raised from a single ear4 ,in this way much of the difficulty due to the great individuality of the plants is overcome1 though that is a factor that must always be recognised and reckoned with4 ,the seeds are sown in damp sawdust--clean deal sawdust1 sifted and mixed up with water into a nice crumbly mass--and as soon as they have germinated and the plantlets are big enough to handle they are put into the culture solutions4 ,barley plants are inserted in the corks with the aid of a little cotton wool 7non-absorbent7 to support them1 care being taken to keep the seed above the level of the water1 though it is below the cork4 ,with peas it is impossible to get a satisfactory crop if the seed is below the cork1 as the plant is very prone to bacterial and fungal infection in its early stages1 and damp cotyledons are fatal for this reason4 ,consequently the mouths of the bottles are covered with stout cartridge paper1 the pea root being inserted through a hole in the paper1 so that the root is in the liquid while the cotyledons rest on the surface4 ,as soon as sufficient growth has been made the papers are replaced by corks1 the remnants of the seeds still being kept on top in the air4 ,other plants are treated according to their individual needs and mode of germination 7,fig4 #a74 ,illustration3 ,fig4 #a4 ,diagrammatic sketches showing methods of setting up water cultures4 ,a4 a4 ,seedling of cereal4 b4 ,cork bored with two holes1 and cut into two pieces through one hole4 c4 ,food solution4 ,b4 a4 ,pea seedling4 b4 ,paper shield which supports the seedling4 c4 ,brown paper cover over bottle of food solution4 ,the constitution of the nutritive solution is important1 and it is becoming more and more evident that different plants have different optima in this respect4 ,for several years a solution of medium strength was used1 containing the following3 ,potassium nitrate #aj gram ,magnesium sulphate #e ,sodium chloride #e ,calcium sulphate #e ,potassium di-hydrogen phosphate #e ,ferric chloride #jd ,distilled water to make up #a litre4 ,this is an excellent solution for barley plants1 giving good and healthy growth4 ,while peas grew very well in it1 they showed some slight signs of over-nutrition4 ,a weaker solution is being tested which gives very good results4 ,peas grow very strongly in it and it also seems to be sufficiently concentrated to allow barley to carry on its growth long enough for the purposes of experiment4 ,the solution is as follows3 ,sodium nitrate #e gram ,potassium nitrate #b ,potassium di-hydrogen phosphate #a ,calcium sulphate #a ,magnesium sulphate #a ,sodium chloride #a ,ferric chloride #jd ,distilled water to make up #a litre4 ,the latter solution was made up so that the quantity of phosphoric acid and potash approximated more or less to the amount of those substances found by analysis in an extract made from a good soil4 ,the experiments are usually carried on for periods varying from #d-aj weeks1 six weeks being the average time4 ,careful notes are made during growth and eventually the plants are removed from the solutions1 the roots are washed in clean water to remove adherent food salts1 and then the plants are dried and weighed either separately or in sets4 ,in order to reduce the error due to the individuality of the plants1 five1 ten or even twenty similar sets are grown in each experimental series1 the mean dry weight being taken finally4 ,also the same experiment is repeated several times before any definite conclusions are drawn4 ,another method of water cultures is used by some investigators1 in which the experiments only last for a few hours or days1 usually #bd-dh hours4 ,while such experiments may not be without value for determining the broader outlines of toxic poisoning1 they fail to show the finer details4 ,the effect of certain strengths of poison is not always immediate4 ,too great concentrations kill the plant at once1 too weak solutions fail to have any appreciable immediate action and so appear indifferent4 ,between the two extremes there exists a range of concentrations of which the effect varies with the plant's growth4 ,a solution may be of such a nature and strength that at first growth is seriously checked1 though later on some recovery may be made1 while it is also possible that a concentration which is apparently indifferent at first may prove more or less toxic or stimulant at a later date1 according to circumstances4 ,consequently too much stress must not be laid upon the results of the short time experiments with regard to the ultimate effect of a poison upon a particular plant4 99 99 99 99 99 ,an examination of the various experimental methods shows that while no one of them is ideal1 yet each of them has a definite contribution to make to the investigation of toxic and stimulant substances4 ,each method aids in the elucidation of the problem from a different standpoint1 and the combination of the results obtained gives one a clearer picture of the truth than could be obtained by one method alone4 ,water cultures1 with their exactitude of quantitative control lead on by way of sand cultures to pot cultures1 and these to field experiments in which the control is largely lost1 but in which the practical application is brought to the front4 ,,chapter ,,iii ,,effect ,,of ,,copper ,,compounds ,i4 ,,presence ,,of ,,copper ,,in ,,plants4 ,copper has been recognised as a normal constituent of certain plants for at least a century1 so much so that in #ahaf ,meissner brought out a paper dealing solely with the copper content of various plant ashes4 ,the ash of ,cardamomum minus1 of the root of ,curcuma longa1 and of 8,paradieskrner#c10 amongst others1 were tested and all yielded copper in very small quantity4 ,meissner was led to conclude that copper is widespread in the vegetable kingdom1 but that it exists in such minute traces that its determination in plants is exceedingly difficult4 ,in #ahba ,phillips made an interesting observation as to the effect of copper on vegetation4 ,some oxide of copper was accidentally put near the roots of a young poplar1 and soon after the plant began to fail4 ,the lower branches died off first1 but the harm gradually spread to the topmost leaves4 ,as a proof that copper had been absorbed by the plant the record tells that the blade of a knife with which a branch was severed was covered with a film of copper where it had been through the branch1 and the death of the plant was attributed to the absorbed copper4 #c ,these are 8grains of ,paradise10 ,guinea grains1 or meleguetta pepper4 ,they are the seeds of ,amomum melegueta and ,a4 ,granum-,paradisi1 ,n4,o4 ,zingiberaceae4 ,after this preliminary breaking of the ground little more seems to have been done for some sixty years1 but from about #ahhj till the present day the association of copper with the vegetable kingdom has been actively investigated in its many aspects4 ,dieulafait 7#ahhj7 showed that the quantity of copper present in the vegetation is largely determined by the nature of the soil1 which thus affects the ease with which the element can be detected and estimated4 ,copper was shown to exist in all plants which grow on soils of 8primary origin0 78roches de la formation primordiale071 the proportion being sufficient to enable it to be recognised with certainty in one gram of ash1 even by means of the ammonia reaction4 ,samples of white oak from the clay soils1 and plants from the dolomitic horizons also gave evidence of copper in one gram of ash1 though less was present than in the first case considered1 but with plants grown on relatively pure chalk #ajj grams of ash had to be examined before copper could be recognised with certainty4 ,e4 ,o4 von ,lippman found traces of copper in beets1 beet leaves1 and beet products2 ,passerini estimated as much as #jhb copper in the stem of chickpea plants1 though he regarded this figure as too high2 ,hattensaur determined #bff ,cu,o in the total ash of ,molinia crulea 7#jjf of total plant1 air-dried74 ,after this ,lehmann 7#ahie1 #ahif7 carried out more exhaustive studies on the subject of detecting and estimating the copper in various articles of food3 wheat1 rye1 barley1 oats1 maize1 buckwheat1 and also in various makes of bread2 potatoes1 beans1 linseed1 salads1 apricots and pears2 cocoa and chocolate4 ,he found that only in those plants which are grown on soil rich in copper does the copper reach any considerable value1 a value which lies far above the quantity present in an ordinary soil4 ,plants from the former soils contained as much as #hc-efj mg4 ,cu in #a kilog4 dry substance1 whereas ordinarily the plants only contained from a trace to #bj mg4 ,apparently the species of the plants concerned seems to be of less importance for their copper content than is the copper content of the soil4 ,the deposition of copper 7in wheat1 buckwheat and paprika7 is chiefly in the stems and leaves1 little being conveyed to the fruits and seeds1 so that a high content of copper in the soil does not necessarily imply the presence of much copper in the grain and seed4 ,the metal is variously distributed among the tissues1 the bark of the wood being the richest of the aerial parts in that substance4 ,the form in which the copper exists in the plant is uncertain and it is suggested that an albuminous copper compound possibly exists4 ,vedrdi 7#ahic7 tackled the problem at about the same time as ,lehmann but from a rather different standpoint4 ,he ratifies the statement as to the absorption of copper by plants1 and going still further he states that in some cases the percentage of copper found in the seed may be four times as great as that occurring in the soil on which the plants grow1 quoting one instance in which the soil contained #jea ,cu,o and the seed #bf ,cu,o4 ,it is assumed that copper must play some physiological rle in the plant1 but no explanation of this action is yet forthcoming4 ,lehmann criticised ,vedrdi's figures of the copper content of certain plant ashes1 and the latter replied in a further paper 7#ahif7 in which he brings most interesting facts to light4 ,the quantity of copper in any species of plant varies with the individuals of that species1 even when grown on the same soil1 in the same year1 and under similar conditions4 ,the copper content of certain plants is put forward as a table1 the years #ahid and #ahie being compared1 and enormous differences are to be noticed in some cases4 ,a quotation of the table will illustrate this more clearly than any amount of explanation4 ,milligrams of copper in #a kilog4 dry matter4 #ahid #ahie _/ _/ 8,seeds0 min4 max4 min4 max4 ,winter wheat #hj #gaj #bjj #fhj ,summer wheat #aij #fcj #aij #bcj ,maize #fj #ij #aj #cj ,barley #hj #abj #aj #gj ,oats #dj #aij #dj #bjj ,buckwheat #afj #fdj #aej #afj 8,fisolen0 7,beans7 #afj #cbj #aaj #aej ,linseed #abj #aej #aaj #aej ,peas #fj #ajj #fj #aaj ,soy ,beans #gj #ajj #gj #hj ,lupins #hj #aij #gj #bij ,mustard seed #gj #acj #fj #gj ,paprika pods #gij #acej #bcj #djj ,,ii4 ,,effect ,,of ,,copper ,,on ,,the ,,growth ,,of ,,higher ,,plants4 #a4 ,toxic effect4 7a7 ,toxic action of copper compounds alone in water cultures4 ,the method of water cultures has been largely applied to determine the relation of copper compounds to plants4 ,twenty years ago 7#ahic7 ,otto discovered the extreme sensitiveness of plants to this poison when grown under such conditions1 as he found that growth was very soon checked in ordinary distilled water which on analysis proved to contain minute traces of copper4 ,controls grown in tap water gave far better plants1 but this superiority was attributed partly to the minute traces of mineral salts in the tap water1 and not only to the absence of the copper which occurred in the distilled water4 ,tests made at ,rothamsted have carried this point still further4 ,pisum sativum1 ,phaseolus vulgaris1 ,triticum vulgare1 ,zea japonica1 ,tropeolum ,lobbianum1 sweet pea 7,american ,queen71 nasturtium1 and cow pea--the first three of these being the species used by ,otto--were grown in 7#a7 ordinary distilled water1 which was found to contain traces of copper1 7#b7 glass distilled water1 for about a month1 till no more growth was possible owing to the lack of nutriment4 ,in every single case the root growth was checked in some degree in the ordinary distilled water1 the roots seeming to the eye to be less healthy and less well developed4 ,in ,pisum1 ,tropeolum and ,zea1 the shoot growth of the coppered plants appeared stronger than that of the controls1 and this was borne out when the dry weights of the plants were obtained4 ,in every other case the coppered plants were inferior1 root and shoot1 to those grown in the pure water4 ,with the first three plants it appears that while the toxic water has a bad effect on the roots1 yet the growth of the shoots is increased4 ,the idea suggests itself that this apparent stimulation is in reality the result of a desperate struggle against adverse circumstances4 ,the roots are the first to respond to the action of the poison1 as they are in actual contact2 their growth is checked1 and hence the water absorption is decreased4 ,no food is available in the water supply from the roots1 so the plant is entirely dependent on the stores laid up in the seed and on the carbon it can derive from the air by photo-synthesis carried on by the green leaves4 ,the result of the root checking in these particular cases seems to be so to stimulate the shoots by some physiological action or other1 that this process of photo-synthesis is hastened1 more carbon being converted into carbo-hydrates1 so that the shoot development is increased1 yielding a greater weight of dry matter4 ,in each of the other cases observed the shoot was obviously not stimulated to increased energy by the poison1 and so the whole plant fell below the normal4 ,other experiments showed that barley roots are peculiarly sensitive to the presence of minute traces of copper1 as very little root growth took place in the copper distilled water1 and root growth was also entirely checked by the presence of one part per million copper sulphate in the pure glass distilled water4 ,yet again1 one litre of pure distilled water was allowed to stand on a small piece of pure metallic copper foil 7about #a 7 for an hour1 and even such water exercised a very considerable retarding influence upon the root-growth1 checking it entirely in some instances4 ,some years before ,true and ,gies published their results1 ,coupin 7#ahih7 had grown wheat seedlings in culture solutions with the addition of copper salts for several days in order to find the fatal concentrations of the different compounds4 ,taking toxic equivalent as meaning 8the minimum weight of salt1 which1 dissolved in #ajj parts of water1 kills the seedling10 the results were as follows3 ,toxic ,containing equivalent copper ,copper bromide 7,cu,br7 #jjdhge #jjachg ,copper chloride 7,cu,cl4#b;aq47 #jjejjj #jjahfe ,copper sulphate 7,cu,s,o4#e;aq47 #jjeeee #jjadae ,copper acetate 7,cu,c,h,o4aq47 #jjegad #jjahbj ,copper nitrate 7,cu,,no4#f;aq47 #jjfajb #jjacab ,these numbers appear to be very close1 so ,coupin considered that it might be permissible to regard the differences as due to the impurities in the salts1 and to the water of crystallisation which may falsify the weights1 so that under these conditions one may believe that all these salts have the same toxicity4 ,this is considerable1 and is evidently due to the copper ion1 the electro-negative ion not intervening with such a feeble dose4 ,a recalculation of these toxic equivalents to determine the actual amount of copper present in each1 gives results that are fairly approximate1 but it is difficult to accept this hypothesis in view of other work in which different salts of the same poison are proved to differ greatly in their action on plant growth4 ,kahlenberg and ,true 7#ahif71 working with ,lupinus albus1 found that the various copper salts1 as sulphate1 chloride and acetate1 were similar in their action upon the roots4 ,plants placed in solutions of these salts of varying strengths for #ae-bd hours showed that in each case #a_/be1fjj gram molecule killed the root1 while with #a_/ea1bjj gram molecule the root was just alive4 ,these workers discuss their results from the standpoint of electrolytic dissociation1 and concur in the opinion that the positive ions of the toxic salt are exceedingly poisonous4 ,the toxicity of the positive ion was again set forth by ,copeland and ,kahlenberg 7#aijj74 ,their water culture experiments were carried on in glass vessels coated internally with paraffin to avoid solution of glass1 and in tests with seedlings of maize1 lupins1 oats and soy beans it was found that such metals as copper1 iron1 zinc and arsenic were almost always fatal to the growth of plants4 ,as a general rule those metals whose salts are toxic1 themselves poison plants when they are present in water4 ,the assumption made was that the injury to plants when cultivated in the presence of pure metals depends on the tendency of the metal to go into solution as a component of chemical compounds and on the specific toxicity of the metallic ion when in solution4 7b7 ,masking effect caused by addition of soluble substances to solutions of copper salts4 ,experiments were carried on with barley1 in which the plants were grown in the various grades of distilled water indicated above1 both with and without the addition of nutrient salts4 ,it was found that the presence of the nutrients exercises a very definite masking effect upon the action of the poisonous substance1 so that the deleterious properties of the toxic substance are materially reduced4 ,later work1 in which known quantities of such toxic salts as copper sulphate were added to pure distilled water showed that in the presence of nutrient salts a plant is able to withstand the action of a much greater concentration of poison4 ,for instance1 a concentration of #a3a1jjj1jjj copper sulphate alone stops all growth in barley1 but1 if nutrient salts are present1 a strength of #a3bej1jjj 7at least four times as great7 does not prevent growth1 though the retarding action is very considerable 7,figs4 #b and #c74 ,illustration3 ,fig4 #b4 ,photograph showing the action of copper sulphate on barley in the presence of nutrient salts4 7,march #eth-,april #aith1 #aijg47 #a4 ,glass distilled water4 #b4 ,copper distilled water4 #c4 #a_/ab1ejj copper sulphate4 #d4 #a_/be1jjj #e4 #a_/ej1jjj #f4 #a_/ajj1jjj #g4 #a_/bej1jjj #h4 #a_/ejj1jjj #i4 #a_/a1jjj1jjj ,illustration3 ,fig4 #c4 ,curve showing the dry weights of a series of barley plants grown in the presence of copper sulphate and nutrient salts4 7,march #acth-,may #crd1 #aijg47 ,,note4 ,in each scale of concentrations represented in the curves a convenient intermediate strength is selected as a unit1 and all other concentrations in the series are expressed in terms of that unit4 ,thus1 with #a_/a1jjj1jjj as the unit a scale of concentrations might run thus3 #aj #a_/ajj1jjj #d #a_/bej1jjj #b #a_/ejj1jjj #a #a_/a1jjj1jjj #je #a_/b1jjj1jjj #ja #a_/aj1jjj1jjj #jje #a_/bj1jjj1jjj #j ,control4 ,these later ,rothamsted results fit in very well with those obtained ten years ago 7#aijc7 by ,true and ,gies in their experiments on the physiological action of some of the heavy metals in mixed solutions4 ,plants of ,lupinus albus were tested for #bd-dh hours with different solutions in which the roots were immersed4 ,given the same strength of the same poison1 the addition of different salts yielded varying results4 ,for instance1 with copper chloride as the toxic agent1 the addition of magnesium chloride did not affect the toxicity1 calcium chloride decreased it1 while sodium chloride slightly increased the poisonous action4 ,calcium sulphate with copper sulphate enabled a plant to withstand four times as much copper as when the latter was used in pure solution4 ,calcium salts in conjunction with those of copper proved generally to accelerate but not to increase growth1 but with silver salts they did not cause any improvement4 ,perhaps this amelioration is in inverse proportion to the activity of the heavy metals4 ,with a complex mixture consisting of five salts--copper sulphate and salts of sodium1 magnesium1 calcium and potassium1 all except calcium being present in concentrations strong enough to interfere with growth if used alone--it was shown that 8as a result of their presence together1 not only is there no addition of poisonous effects1 but a neutralisation of toxicity to such degree as to permit in the mixed solutions a growth-rate equal to or greater than that seen in the check culture40 ,if the concentration of the copper salts was increased1 the other salts remaining the same1 the poisonous activity of the copper became greater than could be neutralised by the other salts4 ,if the copper remained the same and the other salts were diminished by half 7i4e4 below toxic concentration7 the neutralising action of the added salts was markedly less1 and the growth rate never exceeded that of the control4 ,this was apparently due to the action of the unneutralised copper4 ,the indications are that the conspicuously effective part of the molecule is the cation or metal1 and that the anion plays little or no part in causing the toxicity2 in such great dilutions the metals act as free ions4 ,the hypothesis is put forward that interior physiological modifications are responsible for the observed differences in growth rate1 the cell processes being so affected as to bring about different results on cellular growth2 in other words1 the growth rate represents the physiological sum of oppositely acting stimuli or of antagonistic protoplasmic changes where mixtures of salts occur4 ,this is really an extension of ,heald's idea that the toxic effect of a poison is due partly to changes in the turgescence of the cell1 a sudden decrease causing retardation or inhibition of growth1 and partly to a direct action on the protoplasm1 which differs in different plants with the same salt4 ,heald 7#ahif7 went so far as to suggest that the poisonous action is a mere matter of adaptation and adjustment1 since toxic substances are not usually present in soil1 but this assertion is too sweeping to be accepted in its entirety1 although it probably holds good to a certain extent with some species of plants4 ,kahlenberg and ,true 7#ahif7 found that the addition of an organic substance produced the same effect as the addition of some nutrient salt1 in that it reduced the toxicity of the copper salt1 e4g4 in the presence of sugar and potassium hydrate the lupins were able to withstand a concentration of #a_/djj copper sulphate1 part of which reduction of toxicity is attributed to the sugar4 7c7 ,effect of adding insoluble substances to solutions of copper salts4 ,other investigators have shown that the presence of insoluble substances has a similar effect in reducing toxicity to an even greater degree4 ,true and ,oglevee 7#aijd1 #aije7 again used ,lupinus albus as a test plant in the presence of solutions of various poisons in pure distilled water1 copper sulphate1 silver nitrate1 mercuric chloride1 hydrochloric acid1 sodium hydroxide1 thymol and resorcinol all coming under consideration4 ,clean sea sand1 powdered ,bohemian glass1 shredded filter paper1 finely divided paraffin wax and pure unruptured starch grains were respectively added to the solutions1 and seedlings were suspended over glass rods so that their roots were in the solutions for #bd-dh hours4 ,the solids varied in their action on the different poisons2 while the toxic influence of mercuric chloride was reduced by sand and crushed glass1 the action of silver nitrate was modified by nearly all the solids4 ,lupin roots proved unable to withstand an exposure of #bd hours to a concentration of copper sulphate of #a molecular weight in #fj1jjj litres of water 7i4e4 about #a part by weight ,cu,s,o4#e;,h,o in #bdjd parts water71 but the addition of solids caused a great decrease in toxicity4 ,when the amount of copper was diminished an advantage was regularly obtained in favour of the cultures containing the solid bodies4 ,on the whole the ameliorating action of solids is more clearly marked with dilute solutions of strong poisons than with relatively concentrated solutions of weaker poisons4 ,as a general rule1 filter paper and potato starch grains exert a more marked modifying action than the denser bodies1 such as sand1 glass or paraffin4 ,breazeale 7#aijf7 tested the same point with extracts of certain soils which proved toxic to wheat seedlings grown in them as water cultures4 ,the toxicity was wholly or partly removed by the addition of such substances as carbon black1 calcium carbonate or ferric hydrate4 ,other experiments showed that the toxic substances of ordinary distilled water are removed by ferric hydrate and carbon black1 and further that the latter substance will take out copper from copper solutions1 rendering them far less poisonous4 ,further corroboration of ,true and ,oglevee's work was obtained by ,fitch 7#aijf7 who worked in a similar way with fungi1 arriving at the general conclusion that insoluble substances in a solution act as agents of dilution or absorption whereby poisonous ions or molecules are in some way removed4 ,he found that n_/#bef of copper sulphate in beet concoction exercised a stimulating effect on ,penicillium glaucum1 but the addition of fine glass to the solution increased the stimulation1 while large or medium sized pieces did not have the same effect4 ,this action of solid bodies in reducing the deleterious effects of poisonous solutions is attributed to the process of 8adsorption0 whereby a layer of greater molecular density is formed on the surfaces of solids immersed in solutions4 ,the solids presumably withdraw a certain proportion of poisonous ions or molecules from the body of the solution 7retaining them in a molecularly denser layer over their own surfaces71 so that the toxic properties of the solution are reduced owing to the withdrawal of part of the poison from the field of action4 ,in some cases this reduction may be so great as to relieve the solution of its toxic properties1 or even to cause an abnormal acceleration to replace a marked retardation4 ,also1 if the solution is of such a dilution as to cause acceleration of growth in plants1 the addition of insoluble substances may increase this acceleration4 ,the progressive addition of quantities of solids causes progressive dilution of the toxic medium1 the underlying cause of these results being the gradual removal of molecules or ions from the solutions by the insoluble body present4 ,fitch's results are also in accordance with the well-known fact that the physical condition and properties of the added solid play a considerable part in determining its efficacy as an adsorbing agent4 7d7 ,effect of copper on plant growth when present in soils4 ,as has already been shown the toxic property of copper with regard to plants was recognised almost as soon as that element was found to occur in the vegetable kingdom1 but little notice was taken of the discovery for many years4 ,in #ahhb ,f4 ,c4 ,phillips asserted1 as the result of experiments with various cultivated flowering plants1 including geraniums1 coleas1 ageratum1 pansies1 c41 that under favourable conditions plants will absorb small quantities of copper by their roots1 and that such compounds exercise a distinctly retarding influence even if in very small amount1 while if large quantities are present they tend to check root formation1 either killing the plants outright or so far reducing their vitality as seriously to interfere with nutrition and growth4 ,two years later ,knop confirmed both the absorption and the toxicity of copper by his experiments on maize4 ,jensen 7#aijg7 worked with 8artificial0 soils1 under sterile conditions1 using finely ground quartz flour for his medium and wheat for a test plant1 parallel experiments being carried on with solutions4 ,every precaution was taken to ensure sterility--the corks were boiled first in water and then in paraffin1 the seeds were sterilised in #b copper sulphate solution for hour1 washed in sterilised water1 planted in sterilised sphagnum1 the transplanting being done in a sterile chamber into sterilised solutions4 ,the criteria used to determine the toxic and stimulation effects were the total transpiration1 average length of sprout1 the green weight and dry weight of plants4 ,the results obtained with the different substrata showed that it does not follow that a salt highly toxic in solution is equally so in soil1 or that one which holds a relatively high toxic position in soil should occupy the same relative position in solution cultures4 ,for instance1 while in soil cultures nickel compounds were the most toxic of all the substances tried1 in solution cultures silver compounds were more poisonous than nickel4 ,the range of concentrations1 both fatal and accelerating1 was found to be much greater in solution than in soil cultures4 ,in the sand cultures the toxicity of the copper sulphate was found to decrease as the ratio of the quartz sand to the poisonous solution increased1 provided that a water content suitable for growth was present4 ,jensen states that the fatal concentration of copper sulphate in solution cultures is approximately #a_/ajth that of the fatal concentration in his artificial soil4 ,when copper salts are added to soil a complication at once sets in due to the double decomposition which is always likely to occur when any soluble salt is added to soil4 ,the reaction may be graphically expressed as follows1 in a much simplified form-- ,,ab ,,cd ,,ac ,,bd4 ,haselhoff 7#ahib7 extracted several lots of #be kgm4 soil1 each with #be litres of water in which quantities of mixed copper salts varying from #j-bjj mg4 had been dissolved1 the mixture consisting of three parts copper sulphate and one part copper nitrate4 ,this operation was repeated #ae times1 the soils being allowed to drain thoroughly after each treatment1 so that altogether each #be kgm4 soil was extracted with #cge litres water4 ,the drainage waters were analysed1 so that the amount of copper absorbed by the soils could be estimated4 ,it was found that by extracting with water containing such soluble copper salts as sulphate and nitrate1 the food salts of the soil1 especially those of calcium and potassium1 were dissolved and washed out1 copper oxide being retained by the soil4 ,in this way a double action was manifest1 whereby the fertility of the soil was reduced by the loss of plant food1 while its toxicity was increased by the accumulation of copper oxide4 ,so long as the soil contained a good supply of undissolved calcium carbonate the harmful action of the copper-containing water was diminished1 but as soon as the store was exhausted by solution and leaching1 the toxic influence became far more evident4 7e7 ,mode of action of copper on plants4 ,quite early in the investigations on the effect of copper on plants the question arose as to its mode of activity--whether the toxicity was merely due to some mechanical action on the root from outside1 whereby the absorptive power of the root was impaired1 or whether the poisonous substance was absorbed into the plant1 so acting directly on the internal tissues4 ,gorup-,besanez made definite experiments towards ascertaining the truth of these theories as far back as #ahfc1 endeavouring first of all to see whether the plants take up any appreciable quantity of poisons which exist in the soil as mixtures or combinations and which are capable of solution by the cell-sap4 ,salts of arsenic1 copper1 lead1 zinc and mercury were intimately mixed with soil1 #cj grams of the poison being added to #cjg cubic decimetres of soil1 two plants separated by a partition being grown on this quantity4 ,the test plants were ,polygonum ,fagopyrum1 ,pisum sativum1 ,secale cereale and ,panicum italicum1 and all the plants developed strongly and normally except the last named4 ,the ,panicum developed very badly coloured leaves in an arsenic-containing soil1 and the plants were killed soon after they started in soils containing copper4 ,after harvesting1 the crops were analysed and no trace of copper was found in any one of the experimental plants by the methods adopted4 ,also the absorption capacity of different soils for different poisons was shown to vary1 for basic salts are absorbed1 while acids may pass completely through the soil into the drainage water4 ,these results obtained by ,gorup-,besanez are possibly not altogether above criticism1 for later workers showed that copper was absorbed to some extent by plants grown in water cultures1 and if that is so it seems unlikely that no absorption should take place from soil4 ,nevertheless1 the absorption is very slight1 for apparently living protoplasm is very resistant to copper osmotically4 ,otto showed that beans1 maize and peas can have their roots for a long time in a relatively concentrated solution of copper sulphate1 and yet take up very little copper indeed1 but analyses do reveal slight traces after a sufficient interval of time of contact has elapsed4 ,berlese and ,sostegni indicate that the roots of plants grown in water culture in the presence of bicarbonate of copper showed traces of copper4 ,verschaffelt 7#aije7 devised an ingenious method of estimating the toxic limits of plant poisons1 though it is rather difficult to see how the method can be put to practical use with water culture and soil experiments4 ,living tissues increase in weight when put into water on account of the absorption of water4 ,dead tissues do not1 as they have lost their semi-permeable characteristics1 so a decrease in weight takes place owing to part of the water passing out4 ,this principle is applied by ,verschaffelt to determine the 8mortal limit0 of external agents in their action on plant tissues4 ,root of beetroot1 potato tuber1 aloe leaves1 and parts of other plants rich in sugar all came under review4 ,the parts were cut into small pieces weighing about #c-e grams1 dried with filter paper1 weighed1 and plunged into solutions of copper sulphate of varying strengths from #jja-jjd gm4 mol4 per litre1 and left for #bd hours4 ,after drying and again weighing all were heavier owing to the absorption of water4 ,the pieces were then immersed in pure water for another period of #bd hours1 when after drying and weighing1 those from the weaker strengths of copper sulphate 7#jja-jjb7 had absorbed yet more water1 while those from higher concentrations 7#jjc-jjd7 had lost weight4 ,so the author assumes that for such pieces of potato the limit of toxicity lies between #jjb and #jjc gm4 mol4 copper sulphate per litre4 ,these experiments may possibly give some indication as to the action of copper salts on plant roots4 ,so long as the solution of copper salt is dilute enough1 the absorption layer of the root1 acting as a semi-permeable membrane and upheld by the resistant protoplasm1 is able to keep the copper out of the plant and to check its toxicity4 ,as soon as a certain limit is reached the copper exercises a corrosive influence upon the outer layer of the root whereby its functions are impaired1 so that it is no longer able efficiently to resist the entry of the poison4 ,as the concentration increases it is easy to conceive that the harmful action should extend to the protoplasm itself1 so that the vital activities of the plants are seriously interfered with and growth is entirely or partially checked1 death ensuing in the presence of sufficiently high concentrations4 #b4 ,effect of copper on germination4 ,the action of copper on the germination of seeds1 spores and pollen grains has attracted a certain amount of attention1 and although the results are apparently contradictory this is probably due to the different plant organs with which the observers have worked4 7a7 ,seeds4 ,miyajima 7#ahig7 showed that the germinating power of such seeds as ,vicia ,faba1 ,pisum sativum1 and ,zea ,mays was partly destroyed by a #a solution of copper#d1 ,zea ,mays being the most resistant and ,vicia ,faba the least resistant of the three4 ,micheels 7#aijd-e7 stated that water distilled in a tinned copper vessel was more favourable for germination than water from a non-tinned vessel4 ,he suggests that this is due to copper being present in the water in a colloidal form in which the particles are exceedingly small and maintain themselves in the liquid by reason of a uniform disengagement of energy in all directions1 to which energy the influence on germinating seeds must be attributed1 the nature of the suspended substance determining whether the influence be favourable or not4 ,it is questionable1 however1 whether ,micheels was really dealing with a true colloidal solution of copper or with a dilute solution of some copper salt produced by oxidation of the copper vessel from which his distilled water was obtained4 #d ,the ,english translation in ,just's ,bot4 ,jahresber4 speaks only of a 8solution of copper10 and in no case is the specific compound mentioned4 7b7 ,spores and pollen grains4 ,miani 7#aija7 brought fresh ideas to bear upon the problem of the action of copper on living plant cells1 in that he sought to attribute the toxic or stimulant effects to an oligodynamic action1 i4e4 spores and pollen grains were grown in hanging drop cultures in pure glass distilled water with the addition of certain salts or traces of certain metals4 ,while the salts are known to be often disadvantageous to germination1 ,ngeli had asserted that the latter often exerted an oligodynamic action4 ,in some cases pure copper was placed for varying times in the water from which the hanging drop cultures were eventually made1 or tiny bits of copper were placed in the drop itself4 ,various kinds of pollen grains were tested1 and as a rule1 pollen was only taken from one anther in each experiment1 though occasionally it was from several anthers of the same flower4 ,it was generally found that the germination of pollen grains or ,ustilago spores was not hindered by the use of coppered water or by the presence of small bits of copper in the culture solution4 ,the only cases in which some spores or pollen grains were more or less harmed were those in which the water had stood over copper for more than two weeks1 and even so the deleterious effect was chiefly noticeable when the pollen itself was old or derived from flowers in which the anther formation was nearly at an end4 ,as a rule germination was better in the presence of copper1 whether in pure water or food solution1 the stimulus being indicated both by the greater number of germinated grains and by the regular and rapid growth of the pollen tubes4 ,miani attributes this favourable action to the mere presence of the copper1 corroborating ,ngeli's idea of an oligodynamic action4 #c4 ,does copper stimulate higher plants8 ,from the foregoing review it is evident that it is the toxic action of copper that is most to the front1 so far as the higher plants are concerned1 and that little or no evidence of its stimulative action in great dilution has so far been discussed4 ,kanda dealt with this question1 with the deliberate intention of obtaining such evidence1 if it existed4 ,he worked with ,pisum sativum1 var4 arvense1 ,pisum arvense1 ,vicia ,faba1 var4 equine ,pers1 and ,fagopyrum esculentum ,mnch1 which were grown in glass distilled water1 without any food salts1 so that the plants were forced to live on the reserves in the seeds1 which were carefully graded to ensure uniformity of size4 ,it was found that in water cultures copper sulphate solutions down to #jjjjjbdi 7about #a in #dj1afj1jjj7 are harmful to peas1 and still further down to #jjjjjjjbdi 7about #a in #d1jaf1jjj1jjj7 the copper salts act as a poison rather than as a stimulant4 ,against this1 however1 is the statement that in certain soils copper sulphate acts as a stimulant when it is added in solution4 ,jensen again could obtain no stimulation with copper sulphate4 ,the ,rothamsted experiments go to uphold ,kanda's statements as to the failure of copper sulphate to stimulate plants grown in water cultures4 ,peas are perhaps slightly more resistant to the greater strengths of copper sulphate than are barley and buckwheat1 for while #a_/ajj1jjj proves mortal to the latter1 peas will struggle on and fruit in #a_/ej1jjj1 though this strength is very near the limit beyond which no growth can occur 7,fig4 #d74 ,as a general rule1 with barley the depression caused by the poison is still evident with #a_/e1jjj1jjj and #a_/aj1jjj1jjj1 though occasionally these doses act as indifferent doses1 no sign of stimulation appearing in any single instance4 ,with peas again1 even #a_/bj1jjj1jjj copper sulphate is poisonous1 although to the eye there is little to choose between the control plants and those receiving poison up to a concentration of one part in #b million 7,fig4 #e74 ,in the case of buckwheat the matter is still undecided1 as in some experiments apparent stimulation is obtained with #a in #b or #a in #e million copper sulphate1 while in others a consistent depression is evident1 even when the dilution is carried considerably below this limit4 ,the reason for the variation with this particular plant is so far unexplained4 ,illustration3 ,fig4 #d4 ,photograph showing the action of copper sulphate on pea plants in the presence of nutrient salts4 7,oct4 #crd-,dec4 #bjth1 #aiab47 #a4 ,control4 #b4 #a_/ej1jjj copper sulphate4 #c4 #a_/ajj1jjj #d4 #a_/bej1jjj #e4 #a_/ejj1jjj #f4 #a_/a1jjj1jjj #g4 #a_/b1ejj1jjj #h4 #a_/e1jjj1jjj #i4 #a_/aj1jjj1jjj #aj4 #a_/bj1jjj1jjj ,illustration3 ,fig4 #e4 ,curve showing the mean values of the dry weights of four series of pea plants grown in the presence of copper sulphate and nutrient salts4 7,oct4 #crd-,dec4 #bjth1 #aiab47 ,yet1 in spite of all the accumulated evidence as to the consistent toxicity of copper salts in great dilution1 the possibility still remains that the limit of toxicity has not yet been reached1 and that a stimulating concentration does exist1 so that it is still uncertain whether beyond the limits of toxicity copper salts act as indifferent or stimulative agents4 #d4 ,action of copper on organs other than roots4 ,the bulk of the work on the relations of copper with the life-processes of plants has dealt with those cases in which the metal has been supplied to the roots in some form or other1 and many of the results may be said to apply more strictly to the theoretical1 or rather to the purely scientific aspects of the matter1 than to the practical everyday life of the community4 ,this statement is hardly correct1 in that the two lines of work are so inextricably interwoven that the one could not be satisfactorily followed up without a parallel march of progress along the other4 ,in practice1 copper has proved remarkably efficient as a fungicide when applied as sprays in the form of ,bordeaux mixture to infested plants and trees4 ,observations on the action of the fungicide have shown that the physiological processes of the treated plants are also affected to some degree1 and a number of interesting theories and results have been put forward4 7a7 ,effect of copper sprays on leaves4 ,frank and ,krger 7#ahid7 treated potato plants with a #b ,bordeaux mixture1 and obtained a definite improvement in growth1 which they attributed to the direct action of the ,bordeaux mixture upon the activities of the plant4 ,the effect of the copper was most marked in the leaves1 and was chiefly indicated by increase in physiological activity rather than by morphological changes4 ,the structure of the sprayed leaves was not fundamentally changed but they were thicker and stronger in some degree1 while their life was lengthened4 ,apparently1 treatment increased the chlorophyll content1 and1 correlated with this1 was a rise in the assimilatory capacity1 more starch being produced4 ,rise in transpiration was also observed4 ,while the leaves were the organs most affected1 a subsidiary stimulation occurred in the tubers1 since the greater quantity of starch produced required more accommodation for its storage4 ,in different varieties the ratio of tuber formation on treated and untreated plants was #ai3ag and #ag3af4 ,in discussing the meaning of this stimulation these writers1 following the custom then in vogue1 were inclined to hold that it was due to a catalytic rather than to a purely chemical action1 an idea similar to one which later on came much into prominence in connection with the work of ,bertrand's school on manganese1 boron and other substances4 ,the imputed increase in photo-synthesis seems to have met with approval and acceptance1 but nevertheless it did not pass unchallenged4 ,ewert 7#aije7 brought forward a detailed discussion and criticism of the assumption that green plants when treated with ,bordeaux mixture attain a higher assimilation activity than untreated plants4 ,his experiments were made to test the effects of differing conditions of life on plants treated in various ways1 and his conclusions lead him to assert that 8instead of the organic life of the plant being stimulated by treatment with ,bordeaux mixture it is rather hindered40 ,while ,frank and ,krger indicated a rise in transpiration when copper compounds were applied to the leaves as sprays1 ,hattori 7#aija7 attributed part of the toxic effect of copper salts1 when applied to the roots1 to a weakening action on the transpiration stream1 and he maintained that the toxic effect of the copper salts is therefore connected with the humidity of the air4 ,no further confirmation or refutation of this statement has so far come to light4 ,in certain plants the application of cupric solutions as sprays causes a slight increase in the quantity of sugar present in the matured fruits4 ,chuard and ,porchet 7#aijb1 #aijc7 consider that such a modification in the ripe fruit during the process of maturation occurs in all plants which ripen their fruits before leaf-fall begins4 ,injection of solutions of copper salts into the tissues of such plants as the vine causes more vigorous growth1 more intense colour and greater persistence of the leaves2 in other words the copper acts as a stimulant to all the cells of the organism4 ,a similar effect is produced by other metals such as iron or cadmium4 ,by injecting small quantities of cupric salts into the branches of currants an acceleration of the maturation of the fruits was caused1 identical with that obtained by the application of ,bordeaux mixture to the leaves4 ,if the quantity of copper introduced into the vegetable organism was augmented1 the toxic action of the metal began to come into play4 ,these investigators attributed the stimulus1 as shown by the earlier maturation of the fruits1 to a greater activity of all the cells of the organism and not to an excitation exercised only on the chlorophyll functions4 7b7 ,effect of solutions of copper salts on leaves4 ,treboux 7#aijc7 demonstrated the harmful action of solutions of copper salts on leaves by means of experiments on shoots of ,elodea canadensis4 ,the activity of photo-synthesis was measured by the rate of emission of bubbles of oxygen4 ,on placing the shoots first in water1 then in ,n_/#a1jjj1jjj copper sulphate 7#jjjjaei71 there was a reduction from #bj to #ae or #af bubbles in #e minutes4 ,on replacing in water there was an increase to #ah1 but not to #bj1 indicating a permanent injury4 ,with ,n_/#aj1jjj1jjj copper sulphate there was little or no reduction in the number of bubbles4 ,this experiment had an interesting side issue in that it was noticed that not only the concentration1 but also the quantity of fluid was concerned in the toxic action1 indicating that both the proportion and the actual amount of poison available play their part4 ,for instance1 with a shoot #aj cm4 long in #ajj c4c4 solution the plants were only slightly affected by #jjjjae copper sulphate1 but in #ejj c4c4 solution the shoots were killed after some days in #jjjjjae copper sulphate1 a concentration only one-tenth as great4 ,while it is evident that copper sprays have a definite action upon green leaves1 whether favourable or unfavourable1 the question arises as to the means whereby the copper obtains access to the plant in order to take effect4 ,dandeno found that solutions of copper sulphate were absorbed by the leaves of ,ampelopsis1 forming a brown ring4 ,generally speaking inorganic salts in solution are absorbed through both surfaces of the leaves1 whether the leaves are detached or not1 provided the surrounding atmospheric conditions are favourable1 the absorption being usually more ready through the lower surface4 ,dilute solutions applied in drops stimulate the leaf tissue in a ring1 whereas if the solutions are concentrated the entire area covered by the drop is affected4 ,too concentrated solutions of copper sulphate applied to leaves caused scorching1 but if this was avoided while the solution was still strong enough to cause a darkening of green colour after a time1 ,dandeno considered that the action was probably of the nature of a stimulus to growth1 and produced a better development of chlorophyll and protoplasm in the region where the tissues appeared dark to the naked eye1 a conclusion which tallies very closely with that of ,frank and ,krger4 ,amos 7#aijg-h7 experimented to see whether the application of ,bordeaux mixture affected the assimilation of carbon dioxide by the leaves of plants1 and whether any stimulation was produced4 ,brown and ,escombe's methods and apparatus were used and the summarised results indicate that the application of ,bordeaux mixture to the leaves of plants diminishes the assimilation of carbon dioxide by those leaves for a time4 ,the effect gradually passes off1 whatever the age of the leaves may be4 ,the suggestion is made that the stomata are blocked by the ,bordeaux mixture1 so that less air diffuses into the intercellular spaces and less carbon dioxide comes into contact with the absorptive surfaces4 ,if this hypothesis is correct1 the physiological slackening of assimilation is not due to the toxic action of the copper in the ,bordeaux mixture1 but to a mechanical hindrance due to blocking of the stomata4 ,,iii4 ,,effect ,,of ,,copper ,,on ,,certain ,,of ,,the ,,lower ,,plants4 ,on turning to the lower plants1 especially to some species of fungi1 one notices a striking contrast in their behaviour to that of the higher plants4 ,some species of fungi have the power of living and flourishing in the presence of relatively large quantities of copper compounds1 or even of copper or bronze in the solid state4 ,dubois 7#ahij7 found that concentrated solutions of copper sulphate1 neutralised by ammonia1 which were used for the immersion of gelatine plates used in photography1 showed white flocculent masses resembling the mycelium of ,penicillium and ,aspergillus1 which grew rapidly and fructified in ,raulin's solution1 but which remained as mycelium in cupric solutions4 ,the mould proved capable of transforming copper sulphate into malachite in the presence of a piece of bronze1 but it was found that the presence of the latter was not essential for the conversion into basic carbonate4 ,the same result was obtained if the culture liquid was put in contact with a body which prevented it from becoming acid1 fragments of marble acting in this way4 ,copper sulphate solution in the presence of the mould produced a green deposit on the marble1 while without the fungus the solution simply evaporated leaving a blue stain of copper sulphate4 ,trabut 7#ahie7 found that on treating smutty wheat with a #b solution of copper sulphate he obtained a mass of flocculent white mycelium1 whose surface was soon covered with aerial branches bearing pale rose-coloured spores1 and he gave the provisional name of ,penicillium cupricum to the species4 ,on preparing nutritive solutions by steeping a handful of wheat in water for #bd hours1 and then adding various amounts of copper sulphate to them1 ,penicillium was found to vegetate quite well until the amount of copper sulphate reached #i grams in #ajj c4c41 after which the seedings with spores did not develope at all4 ,de ,seynes tested this ,penicillium more exhaustively with different culture media under various conditions and decided that ,trabut was right in only assigning the name ,p4 cupricum provisionally1 as the mould reverts to the form ,p4 glaucum when seeded in a natural medium1 indicating that ,p4 cupricum has not an autonomous existence1 but is ,p4 glaucum which modifies the colour of its conidia under the influence of copper sulphate1 in the same way that it often modifies them in other media4 ,it is noticeable that the mycelium arising from the germination of conidia of ,p4 cupricum in a normal medium has a very poor capacity for producing reproductive organs1 but this diminished activity is attributed not to a special deleterious action of the copper sulphate but to the impulse given to the vegetative functions1 at the expense of the reproductive1 when the spores are seeded in a richer medium than the solutions of copper sulphate which serve as the soil for ,p4 cupricum4 ,ono found that ,aspergillus and ,penicillium are retarded in growth in the higher concentrations of copper sulphate1 but that they are stimulated by weaker strengths4 ,the range of stimulating concentrations is given as from #jjae-jab1 the biggest crop being obtained with both moulds in the strongest of these solutions4 ,hattori gives the optimum as being considerably lower for the two fungi mentioned1 ,penicillium being at its best in a solution of #jjh and ,aspergillus in #jjd4 ,a4 ,richter 7#aija7 opposes this absolutely so far as ,aspergillus niger is concerned4 ,in his experiments copper appears invariably as a depressant1 all concentrations from #a_/aej to #a_/aej1jjj1jjj giving growth below the normal1 no stimulative action ever being observed4 ,zinc however proved to be a definite stimulant and in a mixture of copper and zinc salts in appropriate concentrations the toxic effect of the copper was completely paralysed by the stimulating action of the zinc1 #a_/bjj1jjj zinc salt paralysing or overcoming the copper salt at #a_/aabe4 ,ono states that the optimal quantity of such poisons as copper salts is lower for algae than for fungi1 copper failing to stimulate algae at dilutions which were the most favourable to the growth of fungi4 ,bokorny indicates that silver and copper salts work harm in unusually dilute solutions4 ,attempts have been made to utilise the poisonous action of copper on algae in clearing ponds of those plants4 ,lindsay 7#aiac7 describes experiments carried on in a reservoir infested with ,spirogyra4 ,a quantity of copper sulphate sufficient to make a solution of #a_/ej1jjj1jjj was found necessary to kill off the ,spirogyra1 but it is suggested that the solution was probably weaker before it reached the algae1 owing to the currents of fresh water4 ,anaboena needed #a_/aj1jjj1jjj before it was killed off1 while ,oscillatoria is less sensitive still1 #a_/e1jjj1jjj usually representing the mortal dose1 though #a_/d1jjj1jjj was necessary in some instances4 ,algae seem to be peculiarly sensitive to the copper sulphate1 far more so than the higher plants1 as ,nuphar lutea1 ,menyanthes trifoliata1 and ,polygonum amphibium grew in the water unharmed by the addition of the poisonous substance4 ,for some unexplained reason it seems that 8the concentration of copper sulphate necessary to kill off the algae in the laboratory is five to twenty times as great as that needed to destroy the same species in its natural habitat40 ,conclusion4 ,altogether1 after looking at the question from many points of view1 one is forced to the conclusion that under most typical circumstances copper compounds act as poisons to the higher plants1 and that it is only under particular and peculiar conditions and in very great dilutions that any stimulative action on their part can be clearly demonstrated4 ,,chapter ,,iv ,,effect ,,of ,,zinc ,,compounds ,i4 ,,presence ,,of ,,zinc ,,in ,,plants4 ,the presence of zinc in the ash of certain plants has been recognised for many years1 especially in so far as the vegetation of soils containing much zinc is concerned4 ,risse1 before #ahfe1 stated that most plants when grown on such soils prove to contain greater or less quantities of zinc oxide4 ,he states that the soil at ,altenberg1 near ,aachen1 is very rich in zinc1 which rises as high as #bj in places4 ,the flora of the soil is very diversified and zinc has been determined qualitatively in most and quantitatively in some of the plants4 ,viola tricolor and ,thlaspi alpestre are most characteristic under such circumstances1 both showing such constant habit changes that they resemble new species1 while other plants such as ,armeria vulgaris and ,silene inflata are peculiarly luxuriant4 ,risse's figures of the zinc content of these four plants may prove of interest4 ,the figures are based on the dry weights1 air dried4 ,thlaspi alpestre1 var4 calaminaria4 ,root #fbh ash1 #jafg ,zn,o1 #aff ,zn,o in ash4 ,stem #aage #jche #cbh ,leaves #aade #aej #acab ,flowers #hdi #jbge #cbd ,viola tricolor4 ,root #eei ash1 #jjhe ,zn,o1 #aeb ,zn,o in ash4 ,stem #ajee #jjfe #jfb ,leaves #idb #jaaj #aaf ,flowers #gff #jjge #jih ,armeria vulgaris4 ,root #dgd ash1 #jag ,zn,o1 #ceh ,zn,o in ash4 ,stem #ecg #jjb #jcg ,leaves #icf #jaa #aag ,flowers #fjh #jjg #aae ,silene inflata4 ,root #bga ash1 #jjb ,zn,o1 #jgd ,zn,o in ash4 ,stem ,leaves #aadc #jbb #aib ,flowers ,freytag 7#ahfh7 carried out various experiments on the influence of zinc oxide and its compounds on vegetation1 and found that all plants are capable of absorbing zinc oxide by their roots when grown on soils containing such oxide4 ,generally speaking the zinc is deposited chiefly in the leaves and stems1 very little being found in the seeds1 such minute traces occurring that he stated that the seeds must be harmless for men and animals4 ,the general content of ,zn,o in plants is given as #e-aj of ash1 except in the abnormal case of plants growing on calamine4 ,lechartier and ,bellamy 7#ahgg7 demonstrated the presence of zinc in such food substances as wheat1 ,american maize1 barley and white haricots1 but they failed to find it in maize stems and beetroot1 so they cautiously concluded that if it does occur in the latter cases it must be far less in quantity than in the former4 ,hattensaur 7#ahia7 analysed the ash of ,molinia crulea and discovered the presence of copper1 manganese1 zinc and lead1 zinc oxide forming #bfe of the total ash1 7#jjf of the air dried plant74 ,jensch 7#ahid7 observed that the flora on calamine soils was somewhat scanty1 the chief plants that came under his notice being ,taraxacum officinale1 ,capsella ,bursa-pastoris1 ,plantago lanceolata1 ,tussilago ,farfara1 and ,polygonum aviculare1 all of which showed certain morphological peculiarities4 ,generally speaking the growth of these plants on the calamine soils was weak and poor1 the stems and leaves being very brittle4 ,jensch found that the roots were deformed and showed a tendency towards a plate-like superficial spread of root4 ,the leaves of ,tussilago were uneven in shape and lacked the white hairs on the under side1 the flower stalks were twisted1 while the flowers themselves were a deep saturated yellow colour4 ,the stems of ,polygonum aviculare were much thickened at the nodes1 the leaves weak and rolled in character1 while the flowers were long-stalked1 the calyces being usually of a purple red colour4 ,the following figures are given for the quantities of zinc carbonate 7,zn,c,o7 in the ash of these two plants3-- ,tussilago ,farfara4 ,root ,leaf-stalk ,leaf-blade #bea-cbf #age-afc #bij-bhc ,zn,c,o #afbi-baae #aacf-ajeh #ahhb-ahcf ,zn,o4 ,polygonum aviculare4 ,root ,stem ,leaves #agg-aic #bbe-bhf #abd-adi ,zn,c,o #aadh-abeb #adf-ahef #hjd-ifg ,zn,o4 ,other analyses of plants from zinc soils as against controls from normal soils indicated the high water and high ash content of the zinc plants1 though the dry matter was low1 and it is suggested that the increase of the ash may be connected with a stimulation caused by the zinc salts1 unless it is due to phosphoric-acid hunger1 since the calamine soils concerned are very deficient in phosphorus4 ,javillier 7#aijh c7 corroborated the early statements of ,risse as to the presence of considerable quantities of zinc in certain species of ,viola1 ,thlaspi and ,armeria1 and also he cited a list of other plants in which zinc occurs in some quantity4 ,javillier1 however1 is of opinion that zinc oxide1 like the oxides of iron and manganese1 is very common in plant ash1 being present in all plant organs4 ,zinc is specially abundant in ,coniferae1 where it is probably characteristic1 as is the presence of manganese in the ash and manno-cellulose in the wood4 ,the so-called 8calamine0 plants show great powers of accommodation to large amounts of zinc4 ,klopsch 7#aijh7 analysed #ag species of plants grown on soil in the vicinity of zinc works1 and showed that the plants evidently absorb small quantities of zinc from their surroundings4 ,he also regarded zinc as a normal constituent of certain plants4 ,,ii4 ,,effect ,,of ,,zinc ,,on ,,the ,,growth ,,of ,,higher ,,plants4 #a4 ,toxic effect4 7a7 ,toxic action of zinc salts alone in water cultures4 ,in comparison with copper little work has been done with regard to the action of soluble zinc salts alone on higher plants when grown in water cultures4 ,freytag 7#ahfh7 stated that zinc salts must be very dilute if the plants are not to be harmed1 and that for zinc sulphate the concentrations must not be more than #bjj mg4 per litre 7 #a_/ejjj74 ,baumann 7#ahhe7 carried out further experiments and concluded that zinc salts are far more toxic than ,freytag suspected1 #dd mg4 zinc sulphate per litre#e killing plants of #ac species belonging to #g families 7,coniferae excepted74 ,the various plants withstand the action of the zinc salts in different degrees1 the same concentration killing off the species in different times4 ,with the #dd mg4 zinc sulphate the following results were obtained3-- ,trifolium pratense killed in #af days ,spergula arvensis #ba ,hordeum vulgare #cj ,vicia sativa #ca ,polygonum ,fagopyrum #fj ,beta vulgaris #gf ,onobrychis sativa #aid #e #dd mg4 ,zn,s,o4#g;,h,o #aj mg4 ,zn #a_/bb1gbg ,zn,s,o4#g;,h,o approx4 ,with still less poison1 #bb mg4 zinc sulphate per litre1 all the species mentioned were eventually killed with the exception of ,onobrychis sativa1 while #dd mg4 zinc sulphate seemed to be harmless for all the plants tested except ,raphanus sativus1 which is evidently exceptionally sensitive to this toxic substance4 ,jensen 7#aijg7 again indicated the poisonous action of zinc salts and also found that a relatively small reduction of toxicity was obtained by the addition of finely divided quartz to the solutions4 7b7 ,effect of soluble zinc salts in the presence of nutrients4 ,krauch 7#ahhb7 grew various plants in the presence of nutrient solutions and quantities of zinc sulphate varying from #a to #h gm4 per litre 7 #a_/aj1jjj to #h_/aj1jjj74 ,barley proved to be very sensitive1 even to the weakest strength of the poison1 as the plants soon showed reddish flecks1 while all were dead within six weeks1 the control plants without zinc remaining quite healthy4 ,certain grasses took longer to kill than barley1 those with #d gm4 zinc sulphate per litre dying in about seven weeks1 while #ac weeks elapsed before the others were killed4 ,even after this length of time the plants with #a gm4 zinc sulphate per litre still survived1 although in a very sickly condition4 ,with willow1 again1 even #a gm4 zinc sulphate per litre made the plants very sickly after four weeks1 growth being weak1 the leaves yellow1 and the roots brownish4 ,in this case the solutions were renewed1 but the plants treated with zinc compounds were dead within eight weeks from the start1 the controls being very healthy4 ,the next year 7#ahhc7 ,storp repeated these experiments made by ,krauch and corroborated his results fully4 ,barley and grasses 7timothy and others7 grown in solutions of zinc sulphate1 both with and without nutrients1 soon lost their green colour and became covered with rusty brown flecks1 the barley dying within #ad days1 and the grasses soon after4 ,with willow1 too1 the toxic action was again manifested4 ,true and ,gies 7#aijc7 showed that the addition of calcium salts in appropriate concentrations reduced the toxicity of zinc salts considerably1 a result similar to that which they obtained for copper4 ,recent experiments at ,rothamsted have shown that zinc sulphate is very toxic to barley1 though the plant is able to make some slight amount of growth even in the presence of a solution of the anhydrous salt ,zn,s,o as strong as #a_/ejjj1 rapid improvement occurring as the concentration decreases to #a_/b1ejj1jjj or less 7,fig4 #f74 ,on the whole the higher strengths of zinc sulphate are less poisonous to peas than they are to barley4 ,at a concentration of #a in or #a in million in different experiments the growth was nearly as good as with the control plants1 though it consistently lagged a little way behind until a dilution of #a_/aj1jjj1jjj was reached 7,figs4 #g and #h74 ,incidentally it is very striking to see the desperate efforts that badly poisoned pea plants make to reproduce themselves4 ,growth of the roots is nearly always checked in advance of that of the shoots1 probably on account of the contact of the roots with the poison4 ,in the greater strengths of such poisons as zinc and copper sulphate root growth is checked from the outset1 but usually a very little shoot growth is made1 and one frequently obtains ridiculous little plants about an inch high bearing unhappy and diminutive flowers1 which are occasionally replaced by equally unhappy and miniature fruits4 ,the same thing has also been noticed when unsuccessful attempts have been made to introduce spinach as a test plant for water cultures4 ,illustration3 ,fig4 #f4 ,curve showing the mean value of the dry weights of ten series of barley plants grown in the presence of anhydrous zinc sulphate and nutrient salts4 7,march #bnd-,may #hth1 #aiaa47 ,illustration3 ,fig4 #g4 ,photograph showing the action of anhydrous zinc sulphate on pea plants in the presence of nutrient salts4 7,sept4 #cjth-,dec4 #bjth1 #aiab47 #a4 ,control4 #b4 #a_/e1jjj zinc sulphate4 #c4 #a_/aj1jjj #d4 #a_/ej1jjj #e4 #a_/ajj1jjj #f4 #a_/bej1jjj #g4 #a_/ejj1jjj #h4 #a_/a1jjj1jjj #i4 #a_/b1ejj1jjj ,illustration3 ,fig4 #h4 ,curve showing the mean values of the dry weights of nine series of pea plants grown in the presence of anhydrous zinc sulphate and nutrient salts4 7,may #ahth-,june #bhth1 #aiaj47 7c7 ,effect of zinc compounds on plant growth when they are present in soils4 ,as soon as the presence of zinc in members of the vegetable kingdom was established the question arose as to its effect upon both the plant and the soil4 ,gorup-,besanez 7#ahfc7 grew plants in soil with which #cj grams of metallic poisons such as ,cu,s,o1 ,zn,s,o1 ,hg,o1 were intimately mixed with #cjg litres 78cubik ,decimeter07 of soil#f4 ,on analysing the ash of ,secale cereale1 ,polygonum ,fagopyrum1 and ,pisum sativum after six months growth he failed to detect the presence of zinc in any one of the three4 ,as the results varied with different poisons on different plants he concluded that the absorption capacity of the various kinds of soils for different poisons varies1 that basic salts are absorbed1 while the acid salts may pass completely through the soil in the drainage water4 #f ,this is equivalent to about #a of poison4 ,freytag 7#ahfh7 stated that zinc is retained by the soil in the form of oxide1 which is derived from dilute zinc compounds as they filter through the soil1 by decomposition by the salts of the soil4 ,for field earth the limit of absorption of zinc oxide from zinc sulphate is between #ba-bd of the earth4 ,f4 ,c4 ,phillips 7#ahhb7 corroborated ,freytag's statement as to the absorption of small quantities of zinc by the roots of plants1 but he states as a fact that both lead and zinc may enter plant tissues without causing any disturbance in the growth1 nutrition or functions of the plants1 a conclusion that is obviously incorrect or at least incomplete in view of later work on the subject4 ,his choice of plants was certainly unusual1 including geraniums1 coleas1 ageratums and pansies1 the poison used being zinc carbonate4 ,holdefleiss 7#ahhc7 stated that in spite of a soil content of #b zinc the vegetation was not in any way harmed1 clover fields and meadow lands on zinc soil presenting a normal appearance4 ,this observation was quite inconclusive1 as the author proceeds to say that of the plants that were able to absorb zinc salts without disadvantage the most luxuriant were the so-called zinc plants--the exceptions that prove the rule4 ,two years later ,baumann showed that such insoluble zinc salts as the carbonate and sulphide in the soil cannot hurt plants4 ,these salts are certainly dissolved to some extent by water containing ,,co but solution is hindered by the constitution of the soil4 ,he also found that the various kinds of soil act differently upon zinc solutions1 the absorptive power of pure humus soils 78reinem ,humusboden07 for zinc solutions being the strongest4 ,clay and chalk soils also decompose such solutions energetically1 while poor sandy soils have only a weak power of absorption4 ,this selectivity of absorption may account for the difference in the toxicity of zinc salts to plants in the various soils4 ,storp 7#ahhc7 experimented to determine the changes in the various characters of the soil by the action of zinc salts on it1 and he makes the remarkable statement that in some soils the presence of zinc generates free sulphuric acid1 which is particularly injurious to plant life4 ,grasses1 young oaks and figs showed a decrease in dry weight1 nitrogen and fat1 as the quantity of zinc compounds increased in the water added to the soil4 ,both the quality and the quantity of the crop were adversely affected4 ,this decrease in the dry weight due to the presence of zinc was confirmed by ,jensch later on1 and also by ,nobbe1 ,baessler and ,will 7#ahhd71 who state that both lead and zinc compounds work disadvantageously to vegetation even when they are present in such small quantities that the plants are outwardly sound1 the harmful action appearing in the decrease of dry weight4 ,contrary to ,baumann's opinion1 zinc carbonate is said to be one of the salts that exercises this insidious poisonous action4 ,storp 7#ahhc7 noticed that the direct poisonous action of zinc compounds is largely destroyed by their admixture with soil1 but he suggests that a secondary cause of harm is introduced by the accumulation of insoluble zinc salts1 so that the fertility of the soil is impaired to the detriment of the vegetation4 ,ehrenberg 7#aijh7 throws out a suggestion that zinc is specially harmful to plant life when it occurs in conjunction with ammonia1 but no further evidence has come to light4 7d7 ,mode of action of zinc on plants4 ,the reason for the toxicity of zinc salts when present in soil forced itself upon the attention of some of the early investigators in this field4 ,freytag 7#ahfh7 put forward the hypothesis that the zinc oxide is partly or exclusively absorbed by the roots on account of the cell walls of the root being corroded by the very thin layer of zinc salts lying in contact with it--the same theory as has been held with regard to copper4 ,he stated also that the quantity of zinc oxide taken up by the plant through its roots is strictly limited1 not being proportional to the quantity occurring in the soil1 but varying between narrow limits4 ,krauch 7#ahhb7 found himself unable to accept another hypothesis which at one time found favour1 i4e4 that the zinc salts kill the plants by coagulating the protoplasm4 ,if this were so1 he argued1 no plants at all could grow upon soils containing zinc1 and he was content to leave the cause as one yet to be explained4 ,even at the present time1 thirty years after1 we know very little more about the physiological cause of the toxicity of zinc4 #b4 ,effect of zinc compounds on germination4 ,in the course of his investigations on the influence of zinc on vegetation ,freytag just touched upon the question of seed germination4 ,according to his statement the presence of zinc oxide in the soil does not exercise much influence upon germination and the growth processes of plants4 ,little zinc is stored up in seeds and on this account seeds originating from plants containing zinc germinate quite normally and do not seem to be affected by the peculiar nutritive conditions of the parent plants4 ,in certain cases light seems to have something to do with the harm zinc compounds work on plants4 ,storp found that when clover seeds were germinated in the dark on filter paper moistened with water containing #jbe gm4 ,zn,o per litre 7added in the form of zinc sulphate7 no deleterious action was observed4 ,barley seeds were soaked for four days in 7a7 distilled water1 7b7 water with #i gm4 ,zn,o per litre1 which was frequently changed4 ,these seeds were then placed in the dark on filter papers soaked respectively with water and with the solution containing ,zn,o4 ,so long as no light was admitted1 for a period of eleven days1 germination was uniform in both sets1 but directly the covers were removed the growth of the seeds with zinc ceased almost entirely1 and they did not assume the green colour taken on by the unpoisoned seedlings4 ,with maize the germination was retarded by zinc even in the dark1 but the harmful action of light on the plants with zinc was again established4 ,these results seem to indicate that the formation and activity of chlorophyll is impaired by the toxic agent1 and this hypothesis is borne out by the fact that in many fungi and non-assimilating higher plants the toxic action of zinc is not evident4 ,micheels 7#aijf7 approached the matter from a totally different standpoint1 seeking to discover what influence the valency of a metal has upon the toxicity of its salts4 ,in each of a series of experiments #ajjj c4c4 of decinormal solution of sodium chloride in pure distilled water were used1 with the addition of varying strengths of calcium sulphate4 ,grains of wheat1 which previously had been soaked in distilled water1 were placed in the solutions1 and it was found that the stronger the calcium sulphate solution 7up to #a_/fd normal--the limit of experiment71 the better the growth4 ,the calcium sulphate was then replaced by salts of other bivalent metals1 as zinc1 lead and barium1 with analogous results1 the quantity necessary to obtain the maximum development varying with one and another2 with zinc1 n_/#abh gave the maximum4 ,in this case the toxic action of both sodium chloride and zinc sulphate on germination were considerably reduced by their mutual presence--a result which fits in perfectly with what is known as to the masking effect of soluble substances upon toxic action4 ,the same fact obtains in the animal kingdom1 where ,loeb and others have found that the toxicity of solutions of sodium chloride for marine animals is reduced by the introduction of salts of the bivalent metals4 #c4 ,stimulation induced by zinc compounds4 ,while the toxic action of zinc on the higher plants is so obvious that it forced itself upon the attention of investigators at an early date1 the question of possible stimulus is so much more subtle that it has only come into prominence during the last twelve years1 during which time an extraordinary amount of experimental work has been done with regard to it4 ,one investigator1 ,gustavson1 was somewhat in advance of his time1 for as long ago as #ahha he hinted at the possibility that zinc1 aluminium and other substances might act as stimulants or rather as accelerators4 ,he indicated that the rle of certain mineral salts in the plant economy is to enter into combination with the existing organic compounds1 the resulting product of the reaction aiding in the formation of yet other purely organic compounds which ordinarily require for their formation either a very high temperature or a long time--in other words1 such a mineral salt acts as a kind of accelerator4 ,this work was apparently not followed up immediately1 but it evidently contains the germ of the 8catalytic0 hypothesis of which so much has been made during recent years4 ,the work dealing with zinc as a stimulant to plant growth has yielded such various and apparently contradictory results that the question cannot yet be regarded as settled--it is even still more or less uncertain whether zinc compounds act as stimulants1 or whether they are merely indifferent at concentrations below the toxic doses4 7a7 ,stimulation in water cultures4 ,true and ,gies 7#aijc7 suspended seedlings of ,lupinus albus for #bd-dh hours with their roots in solutions of zinc sulphate and calcium sulphate 7m_/#bef7g1 and found that while zinc sulphate alone at m_/#haib retarded growth1 yet with m_/#bjdh ,zn,s,o and m_/#bef calcium sulphate growth was more than twice as rapid as in controls grown in water1 indicating a marked stimulation4 ,the presence of the calcium exercised a definite ameliorating influence1 reducing the toxicity of zinc to one-sixteenth at most4 ,the hypothesis put forward is that interior physiological modifications are responsible for the observed differences in growth rate1 the cell processes being so affected as to bring about different results on cellular growth--i4e4 that where mixtures of salts are concerned growth rate represents the physiological sum of oppositely acting stimuli or of antagonistic protoplasmic changes4 #g m probably gram molecular weight4 ,kanda 7#aijd7 found that peas were stimulated in dilute solutions of zinc sulphate in the absence of nutrients1 the optimum concentration being between #jjjjjbhg and #jjjjjadce 7about #a in #cd1hdj1jjj and #a in #fi1gjj1jjj71 higher concentrations being poisonous when the solutions were changed every four days4 ,jensen 7#aijg7 stated that he obtained no stimulation at all with water cultures1 even in a solution as dilute as n_/#ajj1jjj 7about #a in #a1bci1jjj71 but he suggested that it was quite possible that in proper concentration the zinc sulphate might prove to be a stimulant4 ,javillier 7#aiaj7 grew wheat in nutritive solutions with quantities of zinc salts containing from #a_/e1jjj1jjj-a_/bej1jjj zinc1 and found that the dry weight of the plant was increased in so far as the stems and leaves were concerned1 though it remained uncertain whether a similar increase occurred in the grain4 ,a consideration of the ,rothamsted experiments shows that up to the present time there is no conclusive evidence that zinc sulphate acts as a stimulant to barley grown in water cultures4 ,as a general rule the growth of those plants with #a_/e1jjj1jjj ,zn,s,o approximates closely to that of the controls4 ,beyond this the growth varies in different experiments4 ,in some cases lower concentrations from #a_/e1jjj1jjj to #a_/ej1jjj1jjj seem to cause some slight improvement in comparison with the normal1 indicating a possible stimulus1 but this improvement is not at all well marked4 ,in other cases these great dilutions are apparently indifferent1 neither a poisonous nor a stimulative action being exerted on the growth of the plant 7,fig4 #f74 ,with peas some increase has been obtained with #a_/bj1jjj1jjj1 and although the rise is only slight1 yet it is possible that it may indicate the setting in of a stimulus which would make itself more strongly felt with still weaker concentrations 7,fig4 #g74 7b7 ,stimulation in sand cultures4 ,while ,jensen denied stimulation in wheat grown in water cultures even when the solutions were as dilute as n_/#ajj1jjj zinc sulphate1 yet he found increase of growth with the same plant in artificial soil 7quartz flour7 to which much stronger solutions of zinc sulphate1 from #en_/#aj1jjj-n_/#aj1jjj1 had been added4 7c7 ,increased growth in soil4 ,nakamura 7#aijd7 dealt with a few plants of agricultural importance1 adding #ja gram anhydrous zinc sulphate to #bcjj grams air-dried soil4 ,the marked individuality in the response of the various plants to the poison is very striking4 ,allium showed signs of increased growth throughout2 ,pisum was apparently improved in the early stages of growth1 but when the dry weights were taken at the end of the experiment no increase manifested itself in the weights of the plants treated with zinc2 with ,hordeum the same quantity of zinc exercised a consistently injurious action4 ,these results with peas and barley corroborate those obtained in the ,rothamsted experiments with water cultures in that zinc sulphate proved to be less toxic to peas than to barley4 ,kanda found that both peas and beans when grown in soil as pot cultures were improved by larger quantities of zinc sulphate than when they were treated as water cultures--a result in full accordance with current knowledge4 ,wheat is evidently peculiarly sensitive to the effects of zinc compounds under differing conditions4 ,javillier 7#aijh c7 pointed out that while wheat is very susceptible to the toxic action of zinc1 yet it can benefit by the presence of sufficiently small quantities of the compounds of the metal4 ,rice is another cereal that is said to respond to the action of zinc sulphate1 as ,roxas1 working in pot cultures with soil both with and without the addition of nutritive salts1 obtained an acceleration of growth on the addition of m_/#ajjj zinc sulphate1 a quantity so remarkably great that it might be expected to act as a toxic rather than as a stimulant4 ,with phanerogams the zinc question is not only concerned with the effect of the metal upon germination1 but also with its effect upon the later growth of the green plants1 and on the physiological functions involving the construction of substances at the expense of mineral elements and the carbon dioxide of the air4 ,javillier holds that the indications are that zinc would prove to be profitable if applied to crops as a 8complementary0 manure4 #d4 ,direct action of zinc salts on leaves4 ,dandeno 7#aijj7 applied zinc sulphate in drops to the leaves of ,ampelopsis1 and found that the solution was not all absorbed by the leaf1 but that a slight dark ring of a yellow colour was produced1 and he was induced to think that some local stimulation was produced if the salt was presented in sufficient dilution4 ,klopsch 7#aijh7 discussed the effect on plant growth of zinc derived from industries producing zinc fumes4 ,zinc oxide from the fumes is deposited on the leaves1 and ,klopsch stated that the rain and dew containing dissolved zinc compounds find entrance to the tissues by way of the stomates and work injury to the plants4 ,against this1 however1 it must be remembered that these same fumes also contain other substances which are admittedly harmful to plant life1 and so the deleterious effect may be partly or even chiefly due to these substances rather than to the zinc4 ,yet it is probable that at least some of the depreciation is due to the zinc4 ,treboux 7#aijc7 tested the effect of zinc sulphate on shoots of ,elodea canadensis4 ,if the shoots were placed in n_/#ajj1jjj 7 #jjjjaf7 zinc sulphate no reduction of assimilation 7as observed by counting the number of oxygen bubbles emitted per minute7 took place1 and replacement in water apparently had no effect either way4 ,when however the shoots were placed in 7#a7 water1 7#b7 #jjjjh zinc sulphate1 7#c7 fresh #jjjjh zinc sulphate1 7#d7 water again1 it was found that while the first solution of zinc sulphate had apparently no effect on assimilation1 yet during the second immersion a gradual reduction in assimilation set in1 which reduction was continued after the return to pure water1 so that the toxic action of the zinc sulphate upon the shoots was clearly demonstrated4 ,,iii4 ,,effect ,,of ,,zinc ,,on ,,certain ,,of ,,the ,,lower ,,plants4 ,among the fungi1 one species stands out in special prominence on account of the great amount of work that has been done on it with regard to its reactions to zinc salts4 ,aspergillus niger ,sterigmatocystis nigra van ,tgh was used as a test plant by ,raulin 7#ahfi71 who evidently considered that zinc was an essential primary constituent of the food solutions of the fungi1 #jg parts zinc sulphate being added to each #aejj parts of water4 ,in his experiments he tested 7#a7 ordinary nutritive solution1 7#b7 nutritive solution with various salts added1 as zinc sulphate1 7#c7 nutritive solution and salts 7as #b7 and also powdered porcelain4 7#b7 gave a crop of ,aspergillus about #ca-ce times better than 7#a71 while 7#c7 was even better still4 ,sulphate of iron also proved stimulating in its action1 but ,raulin stated that zinc cannot replace iron1 as both are essential4 ,ono 7#aijj7 determined the relation between the weight of the mould crop in grams and the quantity of sugar used up in the presence of varying amounts of zinc sulphate4 ,the amount of sugar used was always greater in the crops with #jjcg-jbig zinc sulphate by weight than in the control crops1 indicating a stimulation caused by zinc4 ,richter 7#aija7 carried out rather similar experiments4 ,when grown in solutions without and with #a_/gjj1jjj gram molecule zinc sulphate the dry weights of the mould were practically the same for the first two days1 then the dry weight of the zinc crop shot ahead for a day or two1 a depression setting in on the fifth day4 ,without zinc a less increase took place1 and a similar drop was noticeable about the sixth day4 ,the conclusion drawn is that the stimulation due to the zinc occurs chiefly in the first few days and also that the rise in the sugar consumed is more rapid at first with the moulds treated with zinc4 ,concentrations above #a_/fjj are harmful1 but in weaker solutions zinc is a definite stimulant4 ,coupin 7#aijc7 re-investigated some of ,raulin's work under more antiseptic conditions in order to see what substances were really needed by the mould and whether certain elements declared essential were really so4 ,he concluded that iron and zinc are of no use in the nutrition of ,sterigmatocystis nigra1 but that the zinc retards the development of mycelium when food is abundant1 killing it if it is badly nourished4 ,this denial of stimulation was controverted by ,javillier 7#aijg7 who re-tested ,raulin's solution with extreme care1 growing ,sterigmatocystis in 7a7 normal ,raulin's solution with zinc1 7b7 ,raulin's solution without zinc4 ,the ratio of crops a_/b varied from #bc-ca in four experiments1 vindicating the favourable action of zinc4 ,with regard to the optimum value for zinc the mould seemed to be perfectly indifferent to the presence of medium quantities but very sensitive to extremes1 the maximum weights being reached in dilutions between #a_/aj1jjj1jjj and #a_/bej1jjj1 while quantities above #a_/be1jjj were toxic in their action4 ,at a dilution of #a_/ej1jjj1jjj stimulation was still evident1 though in a less degree than with the optimal concentrations4 ,javillier maintains that zinc is fixed by the fungus1 the whole of the zinc present in dilute solutions being taken up1 only part being utilised in stronger solutions4 ,the value of accordance between the quantity of zinc fixed and the quantity supplied decreases rapidly with increase of concentration4 ,sterigmatocystis is able to fix without harm a quantity of zinc equal to more than #a_/aajj of its weight4 ,zinc is regarded as a catalytic element1 as essential to the well-being of the plant as are the more obvious nutrients1 carbon1 sulphur1 phosphorus1 c41 in spite of the minute traces in which it occurs4 ,a few tests on yeasts made by ,javillier showed that with vegetative yeasts zinc has a specific action1 a consistent increase occurring in the amount of yeast formed and in the amount of sugar consumed as the quantity of zinc increased from #j-a_/aj1jjj1jjj-a_/aj1jjj4 ,with ferment yeast1 however1 zinc exerted no appreciable action4 ,these results lend force to the conclusion of ,richards 7#ahig7 who carried out experiments on fungi with various nutritive media with the addition of certain salts of zinc1 nickel1 manganese1 iron1 c4 ,he considered that his general results showed that the fact of a chemical stimulation of certain metallic salts upon the growth of fungi is established1 although it must not be considered without further investigations that all fungi react in the same degree to the same reagent4 ,conclusion4 ,as matters stand at the present day1 it appears that it is still uncertain whether higher plants grown in water cultures are susceptible to stimulation by zinc salts4 ,if a stimulus does exist1 it must be at exceedingly great dilutions1 but further evidence is needed4 ,in soil cultures1 however1 the fact of increased growth seems to be more firmly established1 certain species responding to zinc salts when used as manure1 though no increase has been obtained with other species4 ,it must always be remembered that the action may be an indirect one4 ,the soil is very complex in its constitution1 and it is impossible to determine the exact action of the added poison upon it1 so that a stimulating effect need not necessarily be due to a direct action of a substance upon the plant1 but it may be the result of more favourable conditions for life induced by the action of the substance upon the soil4 ,among the fungi the stimulation of ,aspergillus niger by minute traces of zinc compounds seems to be well proved1 though again it does not necessarily follow that all fungi will react in the same way to zinc4 ,,chapter ,v ,,effect ,,of ,,arsenic ,,compounds ,i4 ,,presence ,,of ,,arsenic ,,in ,,plants4 ,the occurrence of arsenic as an occasional constituent of plants has been recognised for many years4 ,chatin 7#ahde7 found that if a plant were supplied with arsenical compounds at the roots arsenic was absorbed1 but that it was distributed unequally to the various tissues4 ,the greatest accumulation of the element was in the floral receptacle and the leaves1 while it was scarce in the fruits1 seeds1 stems1 roots and petals4 ,e4 ,davy 7#ahei7 commented on the presence of arsenic in plants cultivated for food4 ,he grew peas in pots and watered them for a short time with a saturated aqueous solution of arsenious acid1 the application being then discontinued4 ,the plants1 apparently uninjured by the treatment1 flowered and formed seeds4 ,on analysis arsenic was readily detected in all parts of the plant1 including the seeds4 ,other analyses revealed the presence of the element in cabbage plants 7from pots7 and turnips 7from field71 both of which had been manured with superphosphate containing some amount of arsenic4 ,this absorption of arsenic by the roots of plants was further established by ,phillips 7#ahhb74 ,various physiological workers have pointed out that this element is frequently or usually present in animal tissues4 ,cern 7#aija7 reached the general conclusion that minimal traces of arsenic can occur in animal organisms1 but that these play no part in the organism and indeed are not constant in their occurrence4 ,bertrand 7#aijb7 established its presence in minute quantities in the thyroid glands of the ox and pig1 hair and nails of the dog1 and the feathers of the goose4 ,gautier and ,clausmann 7#aijd7 realised the constant presence of arsenic in human tissues and recognised that it must inevitably be introduced into the body with the food4 ,this led them to estimate the arsenic present in various animal and vegetable foods1 some of their results being given in the following table4 ,arsenic per #ajj parts fresh substance in gr4 7 thousandth part of a milligram7#h4 ,wheat 7,victoria--complete grain7 #g 7from ,franche ,comt7 #he ,white bread #ga ,whole green cabbage #b ,outside leaves of cabbage #j 7absent7 ,green haricots #j ,turnip #cf ,potatoes #aab #h #j gr41 #a #jjjja mg4 ,arsenic was also found in wine and beer and in considerable quantities in sea water and various kinds of salt4 ,since it cannot be found in some things even in the least traces1 the authors conclude that it is incorrect to say that the element is always present or that it is essential to all living cells4 ,s4 ,h4 ,collins 7#aijb7 found that barley is able to absorb relatively large quantities of arsenic4 ,the plants were grown in pots on soil which originally contained a certain amount of the substance1 and various combinations of arsenic acid1 arsenious acid and superphosphate were added4 ,particulars and details are not given by the author1 except that arsenic was detected by ,reinsch's test in the grains from all the experimental pots1 and in one case 7not specified7 in the upper and lower halves of the straw and in the threshed ears4 ,the analyses of the soil at the close of the experiments showed the presence of #g-bb parts arsenious acid per million4 ,wehmer 7#aiaa7 quotes references to the occurrence of arsenic in ,vitis vinifera4 ,the element was detected in the ash of the must and its presence was attributed to treatment of the plants with arsenical compounds4 ,in this connection it is interesting to note the observation of ,swain and ,harkins 7#aijh71 who1 while acknowledging the absorption of arsenic from the soil by many plants1 yet indicate that in the case of those plants which are exposed to smelter smoke the arsenic is deposited on the vegetation1 and is not absorbed by the latter from the soil4 ,,ii4 ,,effect ,,of ,,arsenic ,,on ,,the ,,growth ,,of ,,higher ,,plants4 #a4 ,toxic effect4 7a7 ,toxic action of arsenic compounds in water cultures in the presence of nutrients4 ,the poisonous action of arsenic on plants has long been recognised4 ,chatin 7#ahde7 gave accounts of tissues poisoned by strong arsenical solutions4 ,nobbe1 ,baessler and ,will 7#ahhd7 carried on water culture experiments with buckwheat1 oats1 maize and alder1 and found that arsenic was a particularly strong poison for these plants4 ,when small quantities of arsenious acid 7,as,o7 were added to the food solutions1 growth was measurably hindered by a concentration of #a_/a1jjj1jjj ,as 7reckoned as ,as74 ,the element only appears in plants in very small quantity and can never be detected in notable quantities4 ,the aerial organs show the effect of arsenical poisoning by intense withering1 interrupted by periods of recovery1 but eventually followed by death4 ,it was also found that if plant roots were exposed to the action of arsenical solutions for a short period1 say ten minutes1 and then were transferred to normal food solutions1 the action of the poison was delayed1 but eventually hindering of growth or death occurred1 according to the strength of the poison used in the first solution4 ,at the same time that ,nobbe1 ,baessler and ,will were establishing the great toxicity of the lower oxide of arsenic1 ,knop 7#ahhd7 was carrying the matter a step further by comparing the action of arsenious and arsenic acid and their derivatives on plant growth4 ,he established the fact that while arsenious acid is a strong poison for maize plants1 arsenic acid in small quantities is not toxic to the roots and that the plants can produce flowers and fruit in its presence4 ,arsenic acid applied as potassium arsenate proved to be harmful to young maize seedlings if the solutions contained #je-a gm4 arsenic acid per litre 7 #a_/-b_/bj1jjj arsenic acid74 ,if however the plants were allowed to form #aj-ae leaves in a pure food solution and then when strongly rooted were transferred to a solution of #je gm4 arsenic acid per litre1 they were found to grow strongly and develope big healthy leaves4 ,careful measurements indicated that the development is unchecked by the addition of the poison1 though arsenic was determined in the ash of the treated plants4 ,stoklasa 7#ahif1 #ahih7 tested the effect of arsenic compounds on plant growth with special attention to their comparative relation to phosphoric acid4 ,he corroborated ,knop's statement as to the greater toxicity of arsenious acid and arsenites in comparison with arsenic acid and arsenates1 stating that #a_/ajj1jjj mol4 wt4 arsenious acid per litre causes definite trouble in plants1 while with arsenic acid #a_/ajjj mol4 wt4 per litre first shows a noticeable toxicity4 ,water culture experiments were made with and without phosphoric acid1 in each case with and without the addition of arsenic and arsenious acid4 ,it was found that the arsenic acid was unable to replace the phosphoric acid1 the plants decaying in the flower in the absence of the latter4 ,in the complete absence of phosphoric acid1 arsenic acid causes a strong production of organic substances up to the flowering time4 ,the following figures were obtained with maize3-- #jjb gm4 ,as,o with ,p,o #bhd gm4 dry wt4 #jje gm4 #bcg #ja gm4 ,as,o #fgcb #dj #fdac #jc ,as,o without ,p,o #ciih #jg #dbac normal solution #abic with #fehd ,comparative experiments with the two arsenical oxides showed that varying times were required to kill different plants4 ,young seedlings were brought into solutions containing #a_/aj1jjj mol4 wt4 arsenious acid 7 #jai gm4 ,as,o per litre7 and the plants died in a very short time4 ,hordeum distichum #df hours ,polygonum ,fagopyrum #hd ,persecaria #ij ,with ten times the strength of arsenic acid 7#a_/ajjj mol4 wt4 #bc gm4 per litre7 the plants took much longer to kill4 ,hordeum distichum #bde days ,polygonum ,fagopyrum #dj ,persecaria #db ,various experiments have been carried on at ,rothamsted with peas and barley4 ,with arsenious acid on barley a depressing influence is manifest even at a concentration of #a_/aj1jjj1jjj1 while no growth at all is possible with #a_/aj1jjj and upwards4 ,apparently the toxic action on the root ceases at a higher strength than on the shoot1 as with #a_/a1jjj1jjj and less the dry weight of the root remains practically constant4 ,at this same strength the shoots look better than the controls1 but this is not apparent in the dry weights 7,figs4 #i and #aj74 ,with peas the depression is again evident to #a_/aj1jjj1jjj1 but the plants are more sensitive to the higher concentrations1 as no growth can take place in the presence of #a_/bej1jjj arsenious acid 7,fig4 #aa74 ,a striking difference is observed with arsenic acid on barley1 as apparently this does not act as a toxic even with such comparatively great concentrations as #a_/ajj1jjj1 though possibly the shoot is slightly depressed by this strength 7,fig4 #ab74 ,illustration3 ,fig4 #i4 ,photograph showing the action of arsenious acid on barley in the presence of nutrient salts4 7,march #afth-,may #ith1 #aiaa47 #a4 ,control4 #b994 #a_/ej1jjj arsenious acid4 #b4 #a_/ajj1jjj #c4 #a_/aej1jjj #d4 #a_/bjj1jjj #e4 #a_/bej1jjj #f4 #a_/ejj1jjj #g4 #a_/a1jjj1jjj #h4 #a_/e1jjj1jjj #i4 #a_/aj1jjj1jjj #aj4 #a_/be1jjj1jjj #aa4 #a_/ej1jjj1jjj ,illustration3 ,fig4 #aj4 ,curve showing the mean value of the dry weights of ten series of barley plants grown in the presence of arsenious acid and nutrient salts4 7,march #afth-,may #ith1 #aiaa47 ,illustration3 ,fig4 #aa4 ,curve showing the mean value of the dry weights of ten series of pea plants grown in the presence of arsenious acid and nutrient salts4 7,june #hth-,july #bast1 #aiaj47 ,illustration3 ,fig4 #ab4 ,curve showing the mean value of the dry weights of ten series of barley plants grown in the presence of arsenic acid and nutrient salts4 7,feb4 #bhth-,april #bdth1 #aiaa47 ,with sodium arsenite the dilutions were carried further1 to #a_/bej1jjj1jjj1 but this still depressed barley to some extent 7,fig4 #ac74 ,with peas the results vary somewhat in the different tests1 the depression with #a_/b1ejj1jjj and less being usually slight1 though occasionally it is much more strongly marked 7,fig4 #ad74 ,in a single series with sodium arsenate barley was apparently unaffected by a concentration of #a_/a1jjj1jjj1 but from this point down to #a_/bej1jjj1jjj a constant depression showed itself1 which was paralleled by a similar depression in the sodium arsenite series from #a_/be1jjj1jjj to #a_/bej1jjj1jjj1 the curves grading downwards instead of up towards the normal4 ,with peas sodium arsenate has little or no action1 though it is just possible that the rather irregular curves indicate a very slight depression below the normal throughout4 ,illustration3 ,fig4 #ac4 ,curve showing the mean value of the dry weights of ten series of barley plants grown in the presence of sodium arsenite and nutrient salts4 7,feb4 #ajth-,april #ahth1 #aiac47 ,illustration3 ,fig4 #ad4 ,curve showing the mean value of the dry weights of ten series of pea plants grown in the presence of sodium arsenite and nutrient salts4 7,june #bgth-,aug4 #ajth1 #aiaa47 7b7 ,toxic effect of arsenic compounds in sand cultures4 ,comparatively few tests seem to have been made as to the action of arsenical solutions in sand cultures4 ,stoklasa 7#ahih7 repeated his water culture work1 using sand as a medium1 and found analogous results by the two methods1 i4e4 that arsenites are far more toxic than arsenates1 and also that the degree of toxicity of a salt varies with the plant to which it is applied1 as was shown by the fact that different plants lived for varying times when treated with similar strengths of solution4 7c7 ,toxic effect of arsenic when applied to soil cultures4 ,daubeny 7#ahfb7 watered barley plants with a solution of arsenious acid1 #a ounce in #aj gallons1 five times in succession1 and found that the crop arrived at maturity about a fortnight earlier than the untreated part of the crop1 though the amount harvested was rather less4 ,with turnips four waterings had no effect upon the time of maturity1 but again the crop was slightly decreased4 ,the analyses made indicated that no arsenic was taken into the tissues1 but that it merely adhered to the external surfaces4 ,gorup-,besanez 7#ahfc7 mixed #cj grams arsenious acid with #cjg litres#i soil1 growing two plants on this quantity of earth4 ,most of his experimental plants 7,polygonum ,fagopyrum1 ,pisum sativum1 and ,secale cereale7 developed normally1 but ,panicum italicum died soon after the plants appeared above the surface1 the leaves being very badly coloured4 ,analyses by ,marsh's test showed no trace of arsenic in #bj grams dry matter from ,secale cereale1 but in #adh grams ,polygonum ,fagopyrum the presence of arsenic was evident1 though the mirror formed was weak4 ,with such a large proportion of arsenious acid in the soil it seems hardly conceivable that the plants were not injured to some extent1 and also it is probable that with more careful analyses arsenic would have been detected in those instances in which its presence was denied4 ,yet it must be remembered that ,davy 7#ahei7 had treated pea plants in pots with a saturated solution of arsenious acid for a short time and had stated that the plants were uninjured4 ,thus both ,gorup-,besanez and ,davy concur in the opinion that ,pisum sativum is indifferent to relatively large quantities of arsenious acid when presented in the soil1 whereas the ,rothamsted experiments show that in water cultures the plant is extremely sensitive even to minute traces of the substance4 ,it is possible that the arsenic in the solution added to the soil enters into combination with other substances1 forming insoluble compounds1 thus being removed from the sphere of action and rendered unable to affect plant life4 ,if this be so1 the apparent immunity of certain plants to arsenious acid is explained4 ,f4 ,c4 ,phillips 7#ahhb71 in his experiments on various flowering plants1 such as geraniums1 coleas and pansies1 found that compounds of arsenic in the soil exercised a distinct poisoning influence1 tending1 when present in large amount1 to check the formation of roots1 so that the vitality of the plant was so far reduced as to interfere with nutrition and growth1 or even to kill it outright4 ,he also stated that traces of arsenic were found in all the plants grown upon the poisoned soil4 #i #cj grams arsenious acid to #cjg 8cubik ,decimeter0 soil about #a4 ,in this connection it is interesting to note that a certain proportion of arsenic is frequently present in the superphosphate used as manure4 ,in view of the known toxicity of arsenical compounds to plant life the question arose as to whether superphosphate manuring would exercise a detrimental influence on account of its arsenic content4 ,experiments carried out by ,stoklasa 7#ahih71 however1 indicate that there is not sufficient arsenic in maximum doses of superphosphate to exercise a toxic action in the field4 7d7 ,physiological considerations4 ,the physiological action of arsenic compounds on plant life early attracted the attention of investigators4 ,chatin 7#ahde7 put forward some rather curious and unexpected considerations with regard to this action4 ,he stated that the effect of arsenic on plant growth is determined more by the constitution and temperament of individual plants than by their age1 and that apparently difference in the sex of plants is of no significance4 ,the chief determining agent1 however1 is the species1 and ,chatin found that as a general rule ,cryptogams are more sensitive than ,phanerogams1 and ,monocotyledons than ,dicotyledons1 as is shown by the fact that under treatment the former perish first4 ,some extreme exceptions exist1 though1 as ,mucor mucedo and ,penicillium glaucum will grow on moist arsenious acid1 whereas leguminous plants are killed by an arsenical solution in a few hours4 ,chatin held the view that elimination of the poison succeeded its absorption1 and that this elimination is complete if the plant lives long enough4 ,here again the species exerts a great influence on the excretory functions of the plants4 ,lupins and ,phaseolus are presumably able to eliminate in six weeks all the arsenious acid they can absorb without dying4 ,most ,dicotyledons need #c-e months1 while ,monocotyledons retain traces of poison for six months after its absorption4 ,lichens are said to eliminate it more slowly still4 ,again1 woody species are longer in freeing themselves than herbaceous1 and young plants carry out the elimination more easily than old plants4 ,the excretory function is influenced by other physiological factors such as dryness and season4 ,the toxic effects and elimination are supposed to act inversely and parallel1 the absorbed arsenious acid combining with alkaline bases1 making a very soluble salt which is excreted by the roots4 ,calcium chloride is given as the antidote to arsenious acid1 all soluble acid being 8neutralised0 by it4 ,this view of the elimination of arsenic apparently did not gain much support1 as no further references to the matter have so far come to light4 ,in view of the work of some modern investigators 7,wilfarth1 ,rmer and ,wimmer7 on the excretion of salts by plant roots1 the idea may prove of fresh interest4 ,chatin also found that moving or still air influenced the working of the poison1 indicating that the external physical conditions affect the toxic action considerably4 ,nearly forty years later ,nobbe1 ,baessler and ,will found that1 if transpiration were hindered by placing plants in a dark or moist room1 it was possible to keep the plants turgescent in arsenic solutions for a long time without thereby increasing the toxic effect later on4 ,the poisonous action proceeds from the roots1 of which the protoplasm is disorganised and the osmotic action hindered4 ,finally1 in the presence of sufficient of the poison1 the root dies without growth4 ,stoklasa 7#ahif1 #ahih7 again found that phanerogamic plants can withstand arsenic poisoning for some time in the dark or in ,,co-free air1 provided that glucose is given in the food solution4 ,the arsenic poisoning is at its maximum during carbon assimilation by means of chlorophyll4 ,the toxic action of arsenious and arsenic acids1 especially in phanerogams1 is due to injury to the chlorophyll activity4 ,the destruction of the living molecule is far more rapid in the chlorophyll apparatus than in the protoplasm of the plant cell4 ,thus it seems that the physiological cause of the toxicity of arsenic is partly a direct action on the root protoplasm1 whereby its osmotic action is hindered1 and partly a detrimental action upon those functions which are directly concerned with the elaboration processes of nutrition4 #b4 ,effect of arsenic compounds on germination4 ,in view of the great toxicity of arsenic to plants in their various stages of development1 one would naturally expect to find a similar action with regard to the germination of the seeds4 ,davy 7#ahei7 casually mentioned cases in which watering with arsenical solutions or dipping seeds in arseniated water prevented germination4 ,heckel 7#ahge7 found that arsenious acid checks germination and kills the embryo at relatively feeble doses1 #be gm4 to #ij gm4 water4#aj ,guthrie and ,helms 7#aijc-d-e7 carried out a systematic series of experiments to test the effect of arsenic compounds upon different farm crops4 ,various amounts of arsenious acid were added to soil in pot experiments1 and the seeds of the several crops were then sown4 ,with barley1 wheat and rye #jaj arsenious acid had little or no effect on germination1 while an increase in the poison exercised a retarding action4 ,maize could withstand #jdj arsenious acid without retardation being perceptible4 ,the aftergrowth with the different crops varied considerably4 ,the wheat plants with #jaj arsenious acid grew all right at first1 but later on they developed weakly4 ,the toxic action increased rapidly as the strength of the poison rose in the different pots4 ,barley proved even more sensitive than wheat1 for even #jje arsenious acid affected the growth adversely4 ,after a time the plants with #jje-jjf recovered and grew strongly1 though not so well as the controls1 but those with #jaj practically died off4 ,rye behaved in the reverse way from wheat4 ,the plants with #jaj were slightly checked at first but later recovered and made growth quite equal to the check plants4 ,growth was stunted with #jbj arsenious acid1 and the plants were killed with #jcj1 so that rye is far less sensitive than barley4 ,with maize the growth was slightly affected with #jje ,as,o1 and increasingly so with greater quantities4 ,it was also found that the action of #jh ,as,o was strongly adverse to the germination of all plants1 and that above this strength germination was altogether prevented4 #aj ,in the present state of our knowledge such a concentration seems relatively strong6 ,the results show very clearly how impossible it is to draw any general conclusions with regard to the action of arsenic compounds on plants1 as they emphasise the strong individuality of the species in their reaction4 #c4 ,do arsenic compounds stimulate higher plants8 ,the question of stimulation due to arsenic does not seem to have engaged the attention of investigators to any extent4 ,water culture experiments at ,rothamsted have so far yielded negative results1 and no stimulation has yet been obtained with any plant1 with the possible exception of white lupin with sodium arsenite4 ,in a single series a stimulus was suggested1 beginning to make itself felt at #a_/ejj1jjj1 rising to an optimum at #a_/aj1jjj1jjj4 ,no stress can be laid on this result1 as it is never safe to draw any certain conclusions without several repetitions of the same experiment4 ,with arsenic acid on barley a possible stimulus is sometimes indicated to the eye1 the plants being fine and of a particularly healthy dark colour1 but this is not corroborated by the dry weights4 ,additional tests were made with peas and barley1 treated with sodium arsenite and arsenate1 the dilutions being carried down to #a_/bej1jjj1jjj1 but no evidence of stimulus was obtained1 so that it hardly seems possible that arsenic can act as a stimulative agent for these two plants when grown in water cultures4 ,it had been thought that the failure to find a stimulation point hitherto might be due to the too great concentration of the toxic substance rather than to the actual inability of the poison to stimulate1 but this hypothesis must now be dismissed so far as these plants are concerned4 ,,iii4 ,,effect ,,of ,,arsenic ,,compounds ,,on ,,certain ,,of ,,the ,,lower ,,plants4 #a4 ,algae4 ,loew 7#ahhc7 was sceptical concerning the specific toxicity of arsenic for plant protoplasm4 ,he was convinced that arsenic and arsenious acid were poisonous to algae1 not because of their specific character as arsenical compounds1 but because of their acid nature1 algae being peculiarly sensitive to any acid1 and he maintained that these substances were not more poisonous than vinegar or citric acid4 ,he placed various species of ,spirogyra in solutions of #b gm4 potassium arsenate per litre water 7#a_/ejjj71 and found that the algae grew well without making any abnormal growth in a fortnight1 showing hardly one dead thread4 ,some of this alga was then transferred to a #a_/ajjj solution of potassium arsenate4 ,this suited it excellently and it increased and the appearance under the microscope was very fresh and strong1 which was attributed more to the potash than to the arsenic acid4 ,loew maintained that for the lower animals and for many of the lower plants arsenic in the form of neutral salts is not a poison4 ,when the differentiation of the protoplasm into certain organs reaches a specific degree in the higher plants1 then the poisonous action of the arsenic compounds comes into play4 ,knop 7#ahhd7 found that certain unicellular green algae grew luxuriantly in a neutral solution supplied with potassium arsenate4 ,bouilhac 7#ahid7 concerned himself chiefly with the possibility of the replacement of phosphates by arsenates4 ,he recognised that the influence of arsenic is not the same on all species of plants1 so he confined his attention to certain of the algae4 ,stichococcus bacillaris ,naegeli was found to live and reproduce itself in a mineral solution containing arsenic acid4 ,even in the presence of phosphoric acid the arsenic acid favours growth1 the best dose being about #a_/ajjj4 ,the arsenic acid is capable of partly replacing phosphoric acid4 ,other species of algae1 ,protococcus infusionum1 ,ulothrix tenerrima1 and ,phormidium ,valderianum invaded the original culture of ,stichococcus from the atmosphere1 but with no arsenic or phosphoric acid their development was poor4 ,the jars with arsenic compounds were invaded by still more species which grew strongly4 ,under these conditions it is evident that these algae are capable of assimilating arsenic1 and the addition of arsenic acid to a solution free from phosphoric acid is sufficient to enable these algae to live satisfactorily1 the arsenates in this case replacing the phosphates4 ,ono 7#aijj7 found that algae are favourably influenced by small doses of poisons1 the optimal quantity for algae being lower than that for fungi4 ,protococcus showed a possible stimulus when grown in concentrations of potassium arsenate varying from #jjjjb-jjje4 ,this possible stimulus is interesting in view of the failure to observe stimulation in higher plants by minute traces of arsenic4 #b4 ,fungi4 ,the effect of arsenic on fungi is of special interest in that it has a direct bearing upon hygienic and commercial interests4 ,gosio 7#ahib1 #ahig1 #aija7 found that certain of the fungi1 ,mucor mucedo and ,aspergillus glaucum1 will grow on various arsenic compounds and exercise a reducing influence on them4 ,these moulds attack all oxygen compounds of arsenic including copper arsenite1 and develope arsenical gases4 ,sulphur compounds of arsenic are not influenced by these fungi4 ,the same moulds would1 if cultivated in soil containing arsenic1 develope hydrogen arsenide4 ,penicillium glaucum has such a strong and definite action on arsenic compounds that he states that there is no doubt of the possibility of poisoning by arsenical gas in a room hung with paper containing arsenic4 ,the compounds are so extraordinarily potent that if a mouse is placed in a vessel in which the mould is strongly developed in the presence of arsenic1 it dies in a few seconds4 ,penicillium brevicaule uses the element in its development as a food substance4 ,if material containing arsenic is placed in contact with dead fungi no reaction occurs4 ,the life activity of the mould is evidently necessary for the reaction by which the arsenic-containing gases are liberated4 ,csapodi 7#ahid7 put forward the earlier results of ,gosio and noted that the so-called arsenical fungicides do not only fail to kill the mould fungi but actually favour their development4 ,this action explains why wallpaper containing arsenic is so disadvantageous in a room4 ,abba 7#ahih7 severely tested ,gosio's method of detecting arsenic by means of growths of ,penicillium brevicaule1 whereby arsenic gases are liberated1 vindicating the method completely1 and establishing the test as an exceptionally delicate one4 ,segale 7#aijd7 applied the same method to the detection of the presence of arsenic in animal tissues4 ,ono 7#aijj7 grew ,penicillium cultures with solutions of potassium arsenate and found no important differences either of depression or stimulation4 ,orlowski 7#aijb-c7 stated that small doses of arsenic 7#a_/ajjj-a_/ajj ,sodium arsen--#aa7 stimulate the growth of ,aspergillus niger1 larger doses up to retard growth1 while kills4 ,spores of the fungus taken from soil containing arsenic are said to possess an immunity against arsenic1 in that they germinate in the presence of an arsenic content which rapidly kills control fungi4 ,this immunity is not specific for arsenic1 but extends also to other poisons4 ,the chemical composition and water content are not altered4 #aa ,the exact compound is not specified in the abstracted paper1 #a_/ajjj-a_/ajj ,natr4 ,ars4 being given4 ,conclusion4 ,the toxic effect of arsenic upon higher plants is much more marked with arsenious acid and its compounds than with arsenic acid and its derivatives4 ,no definite evidence of stimulation has yet been obtained with any arsenic compound1 however great the dilution at which it is applied4 ,with certain algae a stimulus may occur1 and it is possible that arsenic acid is capable of replacing phosphoric acid to some extent under certain conditions4 ,with fungi the toxic effect of great concentrations is marked with certain species1 but there are others which are capable of living happily on arsenical compounds and of liberating highly poisonous arsenic gas4 ,,chapter ,,vi ,,effect ,,of ,,boron ,,compounds ,i4 ,,presence ,,of ,,boron ,,in ,,plants4 ,the first claim to the discovery of boron in plants was put forward in #aheg by ,wittstein and ,apoiger1 who carried out investigations on the ,abyssinian ,saoria 7seeds of ,maasa or ,maessa picta1 ,n4,o4 ,primulaceae#ab74 ,in the course of analyses a crystalline mass was obtained which was found to contain chlorine1 phosphoric acid1 lime1 and boric acid4 ,the discovery apparently attracted little attention and for about another thirty years the matter was again allowed to sink into oblivion4 ,then it came to the front again1 and from #ahhh onwards one investigator after another demonstrated the presence of boron in various plants4 #ab ,according to ,engler's classification this plant belongs to ,n4,o4 ,myrsinaceae4 ,in #ahhh ,baumert detected boron in ,french1 ,german1 and ,spanish wines without exception1 while ,e4 ,o4 von ,lippman 7#ahhh7 demonstrated it in sugar must and also in the leaves and root of the sugar beet4 ,in the latter case the reactions were so definite that the presence of more than a minimal amount of boric acid was conjectured4 ,crampton 7#ahhi7 tested various fruits1 but while he found boron in every part of the watermelon1 he could get no reaction with apples or with certain samples of sugar cane4 ,he predicted1 however1 that the occurrence of boron would prove to be more general in the plant kingdom than had previously been supposed4 ,the next year 7#ahij7 ,hotter extended the work on fruits1 testing for boron in the fruits1 leaves1 and twigs of certain plants1 and finding it in the apple1 pear1 cherry1 raspberry1 fig1 and others4 ,his results indicated that fruits are relatively rich in boron4 ,later on 7#ahie7 ,hotter carried his experiments further1 and he stated that stone fruits are richer in boric acid than are berries and pomes4 ,the accumulation of boron is in the fruit itself1 the other parts of the plant containing little4 ,the quantities of boric acid found in the ash of the various fruits ranged from #eh in the 8,autumn ,reinette0 apple to #jf in figs4 ,bechi had previously 7#ahia7 detected boron in the ash of figs1 love-apple1 and rubus fruits from ,pitecio1 but he attributed this to the presence of boric acid or borates in the soil at the place4 ,passerini 7#ahia7 found traces of boron in the stems of chickpea plants1 while in #ahib ,brand determined boric acid in the ash of beer4 ,in consequence of this various samples of hops were ashed without the addition of any alkali1 and then the ash was distilled with sulphuric acid and methyl alcohol4 ,when tested all the hops showed relatively large quantities of boric acid in comparison with beer1 hence he argued that the boric acid in beer is derived from the hops4 ,boron was discovered in various parts of the hop plant--in the clusters1 leaves1 pedicels1 and stems4 ,jay 7#ahie7 analysed many plants and plant products grown in various soils and waters1 and arrived at the conclusion that boron is of practically universal occurrence in the plant world4 ,of all vegetable liquids wines are the richest in this constituent1 the amount varying from #jji gram to #cc gram per litre4 ,he confirmed ,hotter's statement as to the richness of fruits in this substance1 finding from #aej-fdj grams in #a kgm4 of ash4 ,chrysanthemums and onions1 amongst other plants1 are well off in this respect1 containing #baj-dfj grams per kgm4 of ash4 ,jay also found that the plants vary in their capacity for absorbing boric acid1 those which do so the least easily being ,gramineae 7as wheat1 barley1 rice71 mushrooms and watercress1 the quantity in these plants never exceeding #ejj grams per kgm4 of ash4 ,of all the workers upon boron1 ,agulhon has done the most to extend and concentrate our knowledge of the subject4 ,he used the most refined1 up-to-date methods for the detection and estimation of boric acid1 and so determined its presence in many plants1 including angiosperms1 gymnosperms1 ferns1 algae1 and fungi4 ,tobacco is so rich in boron that it can be detected in the ash of one cigarette4 ,among the plants tested1 the highest percentages of boric acid were found in ,betula alba 7#aage of ash7 and ,laminaria saccharina 7#fhb of ash71 the lowest in ,cannabis sativa 7#abc of ash74 ,generally speaking annual plants and parts of plants seem to have the least boron in the composition of their ashes4 ,in one and the same plant the durable parts like bark and wood are richer than the leaves1 even in evergreen trees4 ,he indicated that plants seem to have a great affinity for boron1 as even when plants are grown on soils in which the boron is practically indetectable they always seem to extract an appreciable quantity of the element4 ,from the foregoing results it is evident that boron is very widespread in the vegetable kingdom1 entering into the composition of many plants in all the great classes4 ,a general impression obtains that its distribution is universal1 and that it will ultimately prove to enter into the composition of practically every plant1 as the scope of the analyses is widened and as methods of detection are improved4 ,on the other hand1 ,agulhon is inclined to think that boron may be a 8particular element10 characteristic of certain groups of individuals or of life under certain conditions4 ,the series of individuals differ among themselves as to their particular needs of nutriment 7in the widest sense7 and doubtless each group has special need of particular elements1 a need that is possibly correlated with morphological and chemical differences4 ,it may well be that boron is one of these elements1 associated with certain vital functions in a way as yet unexplained1 though it may possibly be found to play some part in the formation of vascular tissues1 since it is most abundant in bark and lignified parts4 ,,ii4 ,,effect ,,of ,,boron ,,on ,,the ,,growth ,,of ,,higher ,,plants4 #a4 ,toxic effect4 7a7 ,toxic action of boron compounds in water cultures4 ,excessive quantities of boric acid are decidedly poisonous to plants1 the action being well marked in water cultures4 ,knop 7#ahhd7 found that free boric acid was poisonous in neutral food solutions when present at the rate of #e gram per litre1 but he was not able to detect boron in the ash of the roots of the experimental plants4 ,archangeli 7#ahhe7 placed seedlings of maize1 white lupins1 ,vicia sativa and ,triticum vulgare in solutions of boric acid varying in concentration from #a-je1 with controls in spring water4 ,in the latter case the development was normal1 with #a boric acid the plants were killed1 while it was found that the weaker the solution 7within the indicated limits7 the stronger the root and shoot growth4 ,hotter 7#ahij7 stated that it was known that #a_/bj1jjj boric acid by weight was harmful to soy beans in nutritive solutions4 ,he experimented with peas and maize1 placing the seedlings first in distilled water1 later in nutritive solutions4 ,when the peas were nineteen days old they were transferred to nutritive solutions containing #a_/ajjj-a_/ajj1jjj boric acid by weight per litre1 and within three days the plants with #a_/ajjj showed signs of injury4 ,two days later all the plants showed signs of poisoning in that1 even with the weakest strengths1 the lower leaves were flecked with brown1 especially at the edges1 while with the greater strengths the lower leaves were dead and the flecking had extended to the upper leaves4 ,in eleven days from the start the plants with #a_/ajjj boric acid were completely dead1 while the other plants showed more or less signs of poisoning4 ,the dry matter and ash decreased steadily with the increase in the boric acid1 while the boric acid per #ajj1jjj parts of dry matter increased steadily from #h to #eeg parts4 ,similar experiments were carried on with potassium borate and with borax2 the results showed that1 weight for weight1 borax is less toxic than potassium borate1 which in turn is less toxic than boric acid1 while at a strength of #a_/ajj1jjj there is little to choose between the three poisons4 ,similar results were obtained with maize2 plants treated with boric acid or potassium borate yielded about #bcjj parts boric acid in #ajj1jjj parts dry matter4 ,the general conclusion arrived at by ,hotter was that the effect is not so much that of a general poisoning as of a bleaching of parts of the leaf1 mere traces of boron being harmless4 ,the cause of injury is local inhibition of assimilation and killing of roots in stronger concentrations4 ,increase of the strength of boron raises the toxicity until #a_/ajjj practically inhibits increase in dry substance4 ,the boron was found to be fairly evenly distributed through sound and affected organs4 ,kahlenberg and ,true 7#ahif7 worked with seedlings of ,lupinus albus ,l41 limiting their experiments to those of #ae-bd hours in duration4 ,various combinations of boron and other substances were tested4 ,with boric acid alone #b_/be gram molecule per litre killed the plants1 with #a_/be they were apparently just alive1 while #a_/ajj and less had no injurious effect4 ,boromannitic acid was possibly more poisonous than the boric acid1 while a combination of boric acid and cane sugar proved slightly less toxic4 ,the short duration of these experiments limited their scope considerably1 as with certain concentrations the toxic action would not become evident within the prescribed limits of time4 ,agulhon 7#aiaj a7 worked with sterile nutrient solutions1 and found that the higher strengths of boric acid hindered growth1 #bjj mg4 boric acid per litre rendering growth impossible4 ,he supported ,hotter's idea that the toxic action affects the roots and the formation of chlorophyll1 and he stated that the plants are less green as the dose of boron increases1 plants growing in doses of above #aj mg4 per litre being yellowish4 ,in other experiments he found that at #ajj mg4 boric acid per litre life seems impossible for the plant4 ,the roots seem to be more adversely affected by toxic doses than do the shoots4 ,in control plants ,agulhon determined the stem_/root ratio as #f1 with a little boron as #g1 while the ratio rose to #ac as the dose of the poison increased to #ej-ajj mg4 boron per litre4 ,the ,rothamsted experiments show that boric acid is definitely poisonous to barley down to a strength of #a_/bej1jjj 7,fig4 #ae71 the depressing effect frequently being evident at much smaller concentrations1 while peas can withstand far more of the poison1 the limit of toxicity being about #a_/be-a_/ej thousand 7,fig4 #af74 ,with the greater strengths of poison the lower leaves of both barley and peas are badly damaged4 ,in barley the leaves turn yellow with big brown spots1 giving the leaves a curious1 mottled appearance1 while with peas the poisoning seems to begin at the tip and edge of the leaves1 spreading inwards1 without1 however1 showing the large spots as in barley4 ,so far as chemical tests go at present1 it is very probable that boron is deposited in the leaves in the same way as manganese1 and that this is the cause of the degeneration4 ,as with manganese1 the lower leaves are attacked first1 and the trouble spreads upwards1 one leaf after another being involved4 ,these observations fit in very well with those of ,hotter1 and the hypothesis of direct boron poisoning gains support from the fact that in dilutions which produce stimulation of the shoot the leaves show hardly any sign of dying off1 even after prolonged growth in the solutions4 ,with barley the effects of boron can be seen in the leaves in concentrations as low as #a_/b1ejj1jjj1 and it may be significant that this is the point at which the depressant action of boric acid entirely ceases in many cases4 ,illustration3 ,fig4 #ae4 ,curve showing the mean value of the dry weights of ten series of barley plants grown in the presence of boric acid and nutrient salts4 7,may #ast-,june #bjth1 #aiaa47 ,illustration3 ,fig4 #af4 ,photograph showing the action of boric acid on pea plants in the presence of nutrient salts4 7,sept4 #cjth-,dec4 #bjth1 #aiab47 #a4 ,control4 #b4 #a_/e1jjj boric acid4 #c4 #a_/aj1jjj #d4 #a_/be1jjj #e4 #a_/ej1jjj #f4 #a_/ajj1jjj #g4 #a_/bej1jjj #h4 #a_/ejj1jjj #i4 #a_/a1jjj1jjj ,tests with white lupins gave no conclusive results1 as for some reason it proved very difficult to get satisfactory plants in water cultures4 ,when they are grown under such conditions the roots always tend to get more or less diseased and covered with slime1 probably fungal in nature4 ,in the presence of much boric acid the roots remain in a much healthier condition1 which suggests that the acid has in this case a strong antiseptic action1 and protects the roots4 ,with high concentrations the lower leaves of the plant are badly affected1 just as with peas and barley1 turning brown and withering at an early date4 ,various experiments have been made with yellow lupins1 but these again are very difficult to grow well in water cultures1 as they are apt to drop their leaves for no apparent reason4 ,generally speaking1 the evidence goes to prove that boric acid is toxic down to a concentration of about #ejj parts in #be million4 ,it is difficult to get a true control with which to make comparisons as the plants without boric acid are encumbered with the slime on their roots1 which naturally interferes with normal growth1 while the plants in the presence of boric acid have the unfair advantage due to the probable antiseptic action of the boron4 ,the effect of the boron poisoning is again evident in the dying off of the lower leaves1 which become flaccid and drooping and finally drop off4 ,the lupins grown with boron are very active in the putting forth of lateral roots1 so much so that the cortex of the roots is split along the line of emergence of the laterals1 which are very numerous and crowded4 7b7 ,toxic action of boron compounds in sand cultures4 ,agulhon 7#aiaj a7 moistened #b kgm4 pure sand with #ejj c4c4 nutritive solution for each pot1 and boron was added at the rate of #j1 #ja1 #a1 #aj1 and #ej mg4 boric acid per litre of nutritive solution4 ,twenty wheat seeds were sown in each pot1 and after twelve days the healthy plants in the first four pots were #f-h cm4 high1 but those with the maximum amount of boron showed yellowish leaves only #c cm4 long4 ,after three months' growth the plants were harvested1 when those with most boron were found to have died after making about #aj cm4 growth4 ,the toxic doses in sand proved to be weaker than those in water cultures1 probably because evaporation from the surface of the sand caused concentration of the poisonous liquid4 7c7 ,toxic action of boron compounds in soil experiments4 ,long before any experimental work was done with boron in water cultures1 the poisonous properties of the substance were recognised with regard to plants growing in soil4 ,peligot 7#ahgf7 grew haricots in porous earthenware pots1 the plants being watered by rain and by solutions1 each containing about #b grams per litre of such substances as borax1 borate of potassium1 and boric acid1 other pots receiving various fertilisers1 as potassium nitrate1 sodium nitrate1 c4 ,this quantity of boron completely killed off the plants receiving it1 whether it was applied as free or combined boric acid1 while the fertilised plants completed their development well4 ,on this account the deleterious action was attributed to the boric acid and not to the sodium or potassium base supplied4 ,peligot hinted at the improbability of a substance like boron1 which is so poisonous to plants1 being really innocuous to human beings when it is used as a preservative for foods4 ,nakamura 7#aijc7 also found that borax is harmful in pot cultures if present in large quantities1 #ej mg4 borax per kgm4 of soil exerting a very injurious influence1 while even #aj mg4 per kgm4 did some damage4 ,agulhon 7#aiaj c7 found that the toxic doses of boric acid in soil cultures approached those in nutritive solutions rather than in sand cultures1 a phenomenon that he attributed to the fact that the boric acid was fixed by the soil1 probably as insoluble borate of calcium1 so that the surface concentration obtained with sand cultures was avoided4 ,he found that the ash of plants grown with excess of boron contained more than the normal amount of boron1 while the weight of ash per #ajj dry matter was also increased4 ,he concluded that the plant thus suffers an over-mineralisation and in consequence an augmentation of its hold on water1 so that the fresh weight of the plant may indicate a more favourable action of the boric acid than does the dry weight4 ,other investigators 7,fliche and ,grandeau #ahgd7 had found the same increase in the proportion of ash in chestnut trees grown on too calcareous soil1 so ,agulhon concluded that one is here dealing with a general reaction of plants to an excess of a useful element4 ,other experiments were carried on in the open field1 maize being grown on control plots and on plots receiving #b gm4 boron per square metre4 ,at first the latter plants were behind1 the dose being too strong4 ,eventually1 however1 they pulled up level and the dry weights from the two plots proved to be nearly the same1 the fresh weights being identical4 ,maize is evidently far less sensitive to boron poisoning than are peas and oats1 for with these one-half the original amount of boron 7 #a gm4 per sq4 metre7 proved toxic4 ,interesting results were obtained 7,agulhon #aiaj a7 by repeated experiments with the same soil containing boron4 ,it was found that sand or soil containing a proportion of boron which is lethal or toxic to a first culture will allow much better growth with a second and subsequent crops4 ,repeated experiments on the same soil may show the change from a lethal dose to a toxic one1 thence to an indifferent and finally to an optimum concentration4 ,furthermore 7,agulhon #aiaj b7 the very plants may accustom themselves to greater quantities of boron1 the increased power of resistance being transmitted4 ,he concluded from his experiments that the progeny of the second generation of maize were able to withstand quantities of boron that were toxic to control plants#ac4 ,agulhon once again emphasised the fact that for toxic doses of boron the first symptom is the more or less marked disappearance of chlorophyll1 though the aerial parts are not affected so soon as the roots4 #ac 8,il apparat donc que les graines fournies par des plantes ayant cr en prsence d'une quantit de bore leve prsentent une accoutumance vis--vis de cet lment2 les plants auxquels elles donnent naissance semblent non seulement faire un meilleur emploi des petites doses de bore qui leur sont offertes1 mais encore supportent les doses toxiques plus facilement que les plants tmoins1 issus de graines non accoutumes40 #b4 ,effect of boron compounds on germination4 ,one of the first indications that boron compounds affect the germination of seeds was given by ,heckel 7#ahge7 who found that germination was retarded for #a-c days by weak solutions of borates 7#be gm4 to #bj gm4 water71 and was stopped altogether by stronger solutions 7#fj gm4 to #bj gm4 water74 ,archangeli 7#ahhe7 tested the germination of a variety of seeds of ,leguminosae1 ,gramineae1 and of ,cannabis1 ,iberis1 ,raphanus1 ,collinsia1 and ,linum in the presence of boric acid4 ,the seeds were placed in bowls with solutions of #be1 #e1 and #a boric acid at temperatures ranging from #af-bc ,c4 ,the bowls were covered with glass plates to prevent evaporation and consequent increase of concentration1 controls in spring water being dealt with under similar conditions4 #a boric acid was found to check germination altogether1 and the weaker the concentration the less was the process hindered4 ,morel soaked seeds of haricots and wheat in various solutions of boric acid1 and found that germination was generally hindered or inhibited4 ,the deleterious action diminishes as the strength of the solution or the time of contact diminishes1 but solutions of the same concentration do not act equally on all seeds4 ,boric acid and borax proved to be similar in their action qualitatively4 ,the deleterious effect of strong doses of boric acid on germination was confirmed by ,agulhon 7#aiaj a71 the higher quantities 7above #aj mg4 boric acid per litre7 retarding germination of wheat4 #c4 ,does boron stimulate higher plants8 ,of recent years a few investigators have thrown out hints as to the stimulant action exerted by boron compounds on plants4 ,roxas indicated that ,m_/#ajj1jjj 7,m molecular weight7 of boric acid exercised a favourable action on rice4 ,nakamura 7#aijc7 tested the point by means of pot cultures4 ,peas and spinach plants were grown in soil which received #a and #e mg4 borax per kgm4 ,with peas the #a mg4 exerted evident stimulant action1 as determined by the increase in height of the shoot over that of the control1 #e mg4 seeming to be slightly depressant in action4 ,with spinach a stimulation was observed both in weight and height with a dose of #e mg4 borax per kgm4 ,average weight ,average length of leaves #e mg4 borax #ajce #chb ,control #gb #cdj ,agulhon 7#aiaj c and d7 took the matter up still more definitely and made many tests of various kinds1 in water1 sand and pot cultures4 7a7 ,water cultures4 ,his water cultures were made under sterile conditions1 the seeds when possible being sterilised with corrosive sublimate1 the germinating apparatus being also sterilised4 ,with wheat a stimulant action was evident1 maximum growth being obtained with between #be and #aj mg4 boric acid per litre1 though the dry weight increase did not quite keep pace with that of the fresh weight1 a fact to which previous reference has been made4 ,the chief improvement is in the root1 the stem_/root ratio falling to #e1 as against #f in the control series4 ,visual observation indicated that the roots of plants receiving #e-aj mg4 boric acid per litre are longer than the others1 though they are less rich in adventitious roots4 ,the increased dry weight due to boron may amount to as much as #cj4 7b7 ,sand cultures4 ,agulhon again observed stimulation in this case4 #b kgm4 of sand were moistened with #ejj c4c4 nutritive solution1 varying quantities of boric acid being added in addition4 #a mg4 boric acid per litre of ,n4,s4 7#je mg4 per pot7 gave an increase of #be fresh weight1 and #ge dry weight4 ,the stimulating doses seem to be weaker than in the experiments with liquid media1 probably because the evaporation from the sand increases the concentration of the boric acid at the surface4 ,it was also noticed that the increase of weight varied in experiments made at different times4 ,with oats the stimulating influence is greater than with wheat1 showing that some plants are more sensitive than others to the influence of boron4 ,with radish #a mg4 boric acid per litre exercised a stimulating effect1 the enormous average increase of #fa in fresh weight occurring with this strength1 though this only represented an average increase of #if dry weight4 7c7 ,soil cultures4 ,here again the stimulating action was evident with higher concentrations than in sand cultures1 and ,agulhon obtained good results with strengths that are toxic in sand4 ,the evaporation from earth is not so rapid as from sand1 so that the concentration is not increased1 and also some of the boric acid is withdrawn from the solution by interaction with the soil1 so that the stimulating concentration rises in the scale4 ,in field experiments ,agulhon found that peas were more sensitive to the toxic action of boric acid than is maize4 ,a strength of boric acid 7 #a gm4 ,b per sq4 metre7 that poisoned peas1 gave an increase of #fa fresh weight and #ci dry weight with maize2 half the strength proved to be indifferent for peas1 the improvement with maize equalling #ef increase fresh and #ej increase dry4 ,curiously enough1 judging by appearances in the first experiment1 an unfavourable influence was at work1 though in reality a great stimulation was being caused4 ,colza gave a good increase with similar strengths1 but with turnips #a gm4 ,b per sq4 metre only favoured the aerial parts1 while #e gm4 ,b per sq4 metre only increased root development4 ,agulhon concluded that it is as yet impossible to determine with any precision the exact part that boron plays in the plant economy4 ,he suggests that boron is a 8particulier0 element characteristic of a certain group of individuals or of life under particular conditions4 ,in his summary he argues that each series of individuals adapted to different environments has doubtless need of particular elements1 and that perhaps chemical causes and morphological differences are very closely connected4 ,boron may be of this 8particulier lment0 type in the higher plants of the vegetable kingdom1 and it may be useful commercially as a manurial agent1 the 8catalytic manure0 of ,bertrand and ,agulhon4 ,while the higher concentrations of boric acid proved definitely toxic to both peas and barley in the ,rothamsted water cultures1 some evidence of stimulation was obtained with the lower strengths4 ,with barley the question of stimulation is still an open one1 as below the toxic limit growth seems fairly level in most of the experimental series4 ,the lower limit of toxicity varies from #dj-d parts boric acid per #aj1jjj1jjj according to circumstances4 ,below this critical concentration the boric acid has apparently no action1 either depressant or stimulant1 unless the stimulation should prove to begin at a dilution of #a_/ej1jjj1jjj1 but the evidence on this point is not sufficiently well marked or consistent to be conclusive4 ,this failure to detect stimulation was somewhat unexpected1 as when judged by the eye the plants treated with the lower concentrations of boric acid seemed better than the controls1 and also exhibited a particularly healthy green colouration4 ,peas on the other hand are definitely stimulated with traces of boric acid1 concentrations of #a_/ajj1jjj and less causing an improvement in growth1 while under some experimental conditions even higher amounts of boric acid were beneficial4 ,all the stimulated plants showed the characteristic dark green colour which seems to be associated with the presence of minute traces of boron in the nutritive solution4 ,an interesting morphological feature was the strong development of small side shoots from the base of the plants in the presence of medium amounts of boric acid1 from #a part in #ajj1jjj downwards4 ,this gave rise to a certain bushiness of growth1 which was less evident as the concentration of the stimulant decreased4 ,the general outcome of the tests seems to be that boric acid needs to be supplied in relatively great strength to be fatal to pea plants1 and that the toxic action gives place to a stimulative one high up in the scale of concentration4 ,as far as experiments have already gone it seems as though the stimulation is not a progressive one1 as the effect of #a_/ajj1jjj boric acid is as good as that of #a_/bj1jjj1jjj1 a flat curve connecting the two4 ,this1 however1 needs confirmation4 ,yellow lupins also give some evidence of stimulation with concentrations of about #a_/ej1jjj boric acid1 the improvement being far more strongly marked in some sets of experiments than in others4 ,,iii4 ,,effect ,,of ,,boron ,,compounds ,,on ,,certain ,,of ,,the ,,lower ,,plants4 ,our knowledge of the action of boron on the lower plants is less definite and complete than with regard to the higher plants4 ,morel 7#ahib7 found that boric acid acts as a strong poison to the lower fungi and similar organisms1 their development being completely arrested by very weak solutions of the acid4 ,he suggested1 on this account1 that boric acid might be used in the same way as copper to attack such diseases as mildew1 anthracnose1 c41 which attack useful plants4 ,on the other hand ,loew 7#ahib7 stated that such algae as ,spirogyra and ,vaucheria showed no harmful influence for many weeks when the culture water contained as much as #b 7 #a_/ejj7 boric acid4 ,this may be supplemented by a recent observation at ,rothamsted1 in which certain unicellular green algae 7unidentified71 were found growing at the bottom of a stoppered bottle containing a stock solution of #a_/ajj boric acid4 ,agulhon 7#aiaj a7 dealt chiefly with yeasts and certain ferments1 and found that yeasts grown in culture solutions are not influenced favourably or unfavourably by relatively large quantities of boric acid up to #a gram per litre1 while all development is checked with #aj grams per litre4 ,the presence of boron affects the action of yeast on glucose and galactose4 ,galactose alone is not attacked even after #dj days in the presence of #ff boric acid4 ,when glucose is mixed with the galactose the latter is said to be at first left untouched1 but later it disappears very slowly4 ,boric acid exercises an antiseptic action on lactic ferments1 #e gm4 per litre checking their action sufficiently to enable milk to remain uncoagulated4 ,lactic acid is still produced even with as much boric acid as #aj gm4 per litre4 ,the microbe is not actually killed by the boric acid1 but its development is so arrested that reproduction cannot take place4 ,the same phenomenon was observed with yeast4 ,with moulds again1 while no stimulation could be obtained with small quantities of boric acid1 yet the toxic action does not begin to set in until #e gm4 boric acid per litre are present4 ,thus it appears that such lower organisms as yeast1 lactic ferment and ,aspergillus niger are remarkably indifferent to the action of boric acid1 as is shown by the fact that the toxic dose is remarkably high1 while stimulation effects cannot be observed even in the presence of the smallest quantities yet tried4 ,conclusion4 ,boric acid is less harmful to the growth of higher plants than are the compounds of copper1 zinc1 and arsenic4 ,evidence exists that below a certain limit of concentration boron exercises a favourable influence upon plant growth1 encouraging the formation of stronger roots and shoots4 ,this stimulation is more strongly marked with some species than with others1 peas responding more readily than barley to the action of boric acid4 ,fungi are very indifferent to boron1 whether it is present in large or small quantities1 and there is evidence to show that certain of the green algae can also withstand large quantities of it4 ,,chapter ,,vii ,,effect ,,of ,,manganese ,,compounds ,i4 ,,presence ,,of ,,manganese ,,in ,,plants ,the presence of manganese as a constituent of plant tissues has been known for many years1 and in view of the close association between iron and manganese it was natural that the early investigators should seek for the latter element4 ,de ,saussure 7#ahjd7 gives one of the earliest references to manganese in plant ash1 stating that it occurs in the seeds in less great proportion than in the stems1 and also that the leaves of trees contain less in autumn than in spring4 ,at first oxides of iron and manganese were put together as 8metallic oxides0 and little or no attempt was made to separate them so as to get an idea of their relative abundance4 ,john 7#ahad7 gives a number of rough analyses of plants and indicates the presence of manganese in many plants1 including ,solanum tuberosum1 ,brassica oleracea viridis ,l41 ,conium maculatum1 ,aesculus 7in outer bark71 and ,arundo ,sacchar4 ,no further references presented themselves until #ahdg1 as probably manganese was overlooked and always classed with iron in any analyses made during that time4 ,kane 7#ahdg7 found traces of manganese in the ashes of some samples of flax1 but none in others1 and examinations of the soils on which the plants were grown gave similar results4 ,mayer and ,brazier 7#ahdi7 confirmed this result4 ,herapath 7#ahdi7 analysed the ashes of various culinary vegetables1 finding manganese in cauliflowers1 swede turnips1 beetroot1 and in one variety of potato 7,forty fold74 ,malaguti and ,durocher 7#aheh7 tried to investigate the matter quantitatively4 ,the oxides of iron1 manganese1 and aluminium were all classed together1 and the mean percentage of the three varied from #he-ejf according to the varieties of plants concerned1 ,cruciferae possessing least and ,leguminosae most4 ,different mean results with the same plant were obtained from different soils4 ,wolff 7#ahga7 made other quantitative analyses including ,trapa natans 7#ae ,mn,o71 ,acorus ,calamus 7#aeb ,mn,o71 ,alnus incana 7trace-#gc ,mn,o71 ,pyrus communis 7#bae ,mn,o74 ,many other plants were mentioned by ,wolff as containing manganese4 ,campani 7#ahgf7 found manganese in ash by a method in which it was detected as phosphate of manganese1 and he claimed to be the first to discover manganese in wheat ash4 ,warden 7#ahgh7 found traces of ,mn,o in the ash of opium from ,behar4 ,dunnington 7#ahgh7 detected manganese in the ash of wheat1 #jjadd gm4 7as ,mn,o87 in #cjj grams of 8,dark ,lancaster0 variety1 equivalent to #jbg of the pure ash4 ,the ash was exhausted with nitric acid1 and after separating the iron the ammonium sulphide precipitate was found to contain manganese1 and gave by fusion with nitre and sodium phosphate a violet coloured mass4 ,andreasch 7#ahgh7 found slight traces of ,mn,o in the flowers of ,dianthus caryophyllus1 none occurring elsewhere1 while in ,rosa remontana it appeared in both leaves and flowers4 ,maumen 7#ahhd7 tested many food plants and concluded that some quantity of manganese is frequently present in potato1 rice1 barley1 carrot1 lentil1 pea1 beetroot1 asparagus1 chicory1 most fruits1 tea1 and also in some fodder plants1 as lucerne1 oats1 and sainfoin4 ,ricciardi 7#ahhi71 ,hattensaur 7#ahia7 also added to the list of plants proved to contain manganese4 ,guerin 7#ahig7 studied the manganese content of woody tissues4 ,sawdust was treated with distilled water containing #a caustic potash1 expressed1 and filtered after two or three days4 ,a brown coloured liquid was obtained1 which when treated with a slight excess of hydrochloric acid gave an abundant flocculent precipitate4 ,this precipitate proved to be soluble in pure water1 so it was washed with slightly acidulated distilled water1 and after further purification was analysed4 ,no trace of iron was obtained1 but about #djb ,mn was found4 ,guerin regarded the precipitate as a 8nucleinic0 combination1 which he supposed to occur generally in wood and to contain the manganese present in the woody tissues of all plants4 ,schlagdenhauffen and ,reeb 7#aijd7 detected manganese in a petrol extract of such cereals as barley1 oats1 and maize1 and since inorganic salts of manganese are not soluble in such liquids as ether or petrol they concluded that the manganese must be present in the plant in organic combination1 thereby upholding ,guerin's view4 ,loew and ,seiroku ,honda 7#aijd7 give a table of ,mn,o in the ashes of certain trees4 ,this is very high in some cases1 rising to #aabe in the ash of beech leaves1 #fgc in birch leaves1 and #edh in chestnut fruits4 ,gssl 7#aije7 gives lists of the distribution of manganese in plants1 both ,thallophytes and ,phanerogams1 indicating the presence of much or little of the element4 ,as a rule1 he states1 marsh and water plants gather up more manganese than do land plants4 ,the ,gymnosperms seem to be particularly rich in their manganese content4 ,schrder 7#ahgh7 tested for the element in firs and pines and found the following amounts of ,mn,o4 ,in #ajj parts ash4 ,in #ajjj parts dry matter4 ,fir ,pine ,fir ,pine #ccah #acdf #bgf #gg ,he gave a table of detailed analyses showing the differing proportions of manganese in the different parts of the fir4 ,baker and ,smith 7#aiaj7 paid special attention to manganese in their exhaustive work on the ,pines of ,australia4 ,they state that 8in the anatomical investigations of the timber1 bark1 and leaves of the various species1 there was found to be present1 in a more or less degree1 a naturally brownish-bronze coloured substance1 which invariably stained dark brown or almost black with haematoxylin40 ,this substance on careful investigation proved to be a compound of manganese4 ,the quantity present varies with the species and also with the plant organs4 ,the different species of the genus ,callitris show variable percentages of manganese from a maximum of #jbcj in ,c4 gracilis1 to a minimum of #jjaj in ,c4 robusta4 ,the percentage of manganese in ,australian ,coniferae other than ,callitris is given by the authors in the following table3 ,ash of timber of ,agathis robusta #jade ,mn4 ,araucaria ,cunninghamii #jjed ,araucaria ,bidwilli #jjgg ,actinostrobus pyramidalis #jjgg ,podocarpus elata #jjjb ,dacrydium ,franklini #jabi ,athrotaxis selaginoides #jjai ,phyllocladus rhomboidalis #jade ,air-dried black gum of ,agathis robusta #jjjdf ,araucaria ,cunninghamii #jjjch ,baker and ,smith assume that manganese is essential to the production of the most complete growth of ,coniferae4 ,the element is found in these plants even when they grow on soils containing only traces of manganese and it is suggested that possibly the excess or deficiency of manganese in the soil helps to govern the location of certain of the ,australian ,coniferae4 ,the authors conclude that manganese may be essential to the growth of these plants1 and that its association with plant life may be considered to date back to past geological time1 as is indicated by plates illustrating fossil woods4 ,,ii4 ,,effect ,,of ,,manganese ,,on ,,the ,,growth ,,of ,,higher ,,plants4 #a4 ,toxic effect4 7a7 ,toxic action of manganese compounds in the presence of soluble nutrients4 ,little work seems to have been done on the action of manganese compounds in water cultures4 ,knop 7#ahhd7 just indicated that manganese compounds had no effect on maize1 but gave no details4 ,japanese investigators touched on the matter in the course of their extensive experiments with this element4 ,as 7#aijb7 found that the greater concentrations of manganese sulphate exercised an injurious influence on barley4 ,even in solutions with as little as #jjb manganese sulphate 7 #a_/ej1jjj ,mn,s,o7 the roots gradually turned brown1 the lower leaves following suit4 ,the brown colour was concentrated at certain points of the leaves1 and microscopical examination showed that the membranes of the epidermal cells1 and in some cases the nuclei1 were stained deeply brown4 ,the greatest concentration endured by barley without injury seemed to be about #ja per #ajjj #a_/ajj1jjj4 ,the presence of iron in the food solutions seems to counteract the effect of the manganese to some extent by delaying the yellowing of the leaves4 ,wheat proved very similar to barley in its reactions1 though more iron is necessary to give good healthy growth4 ,as states that wheat is able to overcome the injurious action of manganese much more readily than is barley4 ,with peas the yellowing of the leaves was delayed1 probably on account of a sufficient supply of iron in the reserve stores of the seeds4 ,loew and ,sawa 7#aijb7 found that #be #a_/djj ,mn,s,o 7anhydrous7 kills pea plants within five days and that the green colour is gradually affected with more dilute solutions4 ,barley and soy beans were grown in nutritive solutions with either iron sulphate or manganese sulphate or both 7#ja ,fe,s,o1 #jb ,mn,s,o1 #ja ,fe,s,o #jb ,mn,s,o74 ,at first the growth was increased by the action of two salts together1 but eventually the shoots turned yellowish1 and assimilation was depressed1 so that decreased nutrition led to relaxation in the speed of growth1 indicating the toxic action due to the manganese sulphate4 ,the ,rothamsted experiments supported ,as's work on the action of manganese sulphate on barley1 concentrations of the salt above #a_/ajj1jjj having a retarding influence on the growth1 the roots being coloured brown and the leaves also showing discolouration4 ,at an early stage in growth the lower leaves of the plants receiving the most poison began to be flecked with brown spots1 which were at first attributed to an attack of rust4 ,suspicion was soon aroused1 however1 and a closer microscopic investigation showed that no disease was present1 but that the cells in the affected spots were dead and brown1 though they retained their shape4 ,the dead cells at first occurred in small patches1 which spread and coalesced until ultimately the whole leaf was involved4 ,some of the affected leaves were detached and fused with a mixture of sodium carbonate and potassium nitrate4 ,on dissolving up the resulting mass with water a green colouration was obtained1 indicating the presence of manganese in the leaves4 ,this shows that the manganese is taken up by the roots1 transferred to the leaves and then deposited in them1 the lower leaves being the first affected4 ,the presence of manganese in the nutritive solution retarded the ripening of the grain to some extent1 as when the grains from the control plants were hard and ripe1 those from plants treated with #a_/aj1jjj ,mn,s,o were green1 those with #a_/ajj1jjj were a mixture of ripe1 half-ripe1 and green grains1 while plants which had received #a_/a1jjj1jjj ,mn,s,o possessed ripe grains4 ,peas give similar results to barley so far as the vegetative growth is concerned1 the same retardation with the higher concentrations being observed1 while the brown discoloured patches in the lower leaves are much in evidence4 ,all traces of manganese in the leaves disappear when the concentration falls to #a_/bej1jjj4 ,on the whole peas are more sensitive to manganese poisoning than is barley1 and the higher strengths of manganese prove more deleterious to them4 7b7 ,toxic action of manganese compounds in sand cultures4 ,little work has been done on this aspect of the problem4 ,prince de ,salm ,horstmar 7#ahea7 grew oats in sand with various combinations of nitrogenous substances and inorganic mineral salts4 ,he stated that until the time of fruit formation manganese does not seem to be essential to the oat unless iron is in excess in the substratum4 7c7 ,toxic action of manganese compounds in soil cultures4 ,a large body of work has been done with manganese in soil cultures1 but the toxic effect is hardly indicated1 possibly because it is less manifest under soil conditions1 possibly because the observation of the toxic action has been almost completely overshadowed by the interest in the stimulation observed under the same circumstances4 ,namba stated that #e gm4 ,mn,s,o added to #h kgm4 ,japanese soil exerted a depressing influence on the growth of various plants4 ,the ,hills ,experiments 7#aijc7 indicated some toxic effect4 ,various soluble and insoluble salts of manganese were added to soil in pots at the rate of #b cwt4 per acre1 wheat being sown4 ,on the whole the plants from untreated pots were as good as any with manganese except those that received manganese nitrate or phosphate4 ,manganese iodide distinctly retarded growth4 ,the plants that grew did well eventually1 but development of the ear was greatly or entirely retarded4 ,if the seeds were soaked in the iodide1 a concentration of #aj was found to be harmful1 #e allowing normal growth4 ,similar experiments with barley showed that plants treated with manganese carbonate and sulphate were both inferior to the untreated plants2 with iodide less plants were obtained and their development was abnormal4 ,soaking the seeds in the iodide1 even in #aj solution1 did not do damage as it did with wheat4 ,the oxides were apparently innocuous1 but gave no increase either in corn or straw4 ,kelley 7#aiji7 found that on soils in ,hawaii in which excessive quantities of manganese are present 7#efa ,mn,o7 pineapples do not flourish1 but turn yellow and produce poor fruits1 and also that if rather less manganese is present 7#acf ,mn,o7 the pineapples show the toxic effect by yellowing during the winter months1 but they recover completely during the hot summer months4 ,kelley also observed that the deleterious effect is hardly noticeable during the first twelve months of growth1 and that after a time a darkening occurs in the colour of the soil1 which he attributes to some change in the constitution of the manganese compounds4 ,some interesting observations were made by ,guthrie and ,cohen 7#aiaj7 on certain ,australian soils4 ,a bowling green that was initially covered with a healthy mat of couch grass developed a number of small patches after about three years growth1 on which the grass died off4 ,no reason was apparent for this phenomenon1 as the cultural conditions were uniform and to all appearances the soil over the whole area was similar in character4 ,analyses of soil samples from the dead patches and from the neighbouring healthy parts of the green showed that the chemical composition in both cases was practically the same1 except that while no manganese occurred in the soil from the unharmed part1 as much as #bed ,mn,o was found in that from the dead patches4 ,as no other differences were found it was argued that the manganese1 present in such large quantities1 acted as a toxic agent and killed off the grass4 ,other instances of manganese poisoning in which wheat and barley were affected are quoted by these authors1 the analytical results indicating that possibly barley is able to withstand without injury a greater quantity of manganese compounds in the soil than is wheat4 #b4 ,effect of manganese compounds on germination4 ,nazari 7#aiaj7 rolled wheat grains in a paste of manganese dioxide1 iron sesquioxide 7both with and without organic matter71 and in what he terms 8artificial oxydases40 ,the seeds rolled in the last-named showed the greatest energy in germination1 while those with manganese gave an appreciable acceleration4 ,the presence of organic matter decreased the action of manganese4 ,the plants from the manganese seedlings gave an increased yield in both straw and grain1 while those treated with sesquioxide of iron showed no gain over the check plants4 ,the ,hills ,experiments yielded some information as to the differing effects of various compounds of manganese on germination4 ,with wheat plants in pot experiments manganese oxide 7,mn,o7 distinctly retarded germination when applied at the rate of #b cwt4 per acre4 ,with barley ,mn,o1 manganese carbonate and sulphate all retarded germination1 while with the iodide #ej of the seeds were entirely prevented from germinating4 #c4 ,does manganese stimulate higher plants8 ,with manganese the evidence in favour of stimulation is more weighty than with such poisons as copper1 zinc and arsenic1 and the literature on the subject is correspondingly plentiful4 7a7 ,stimulation in water cultures4 ,while ,as 7#aijb7 asserted that plants can develope normally in water cultures in the absence of any trace of manganese1 he further stated that manganese compounds exercise both an injurious and a stimulant action on plants4 ,with increasing dilution of the compound the deleterious action diminishes1 while the stimulant action increases1 and a dilution can be reached in which only the favourable influence of the manganese becomes obvious4 ,the addition of #jjb manganese sulphate 7 #a_/ej1jjj7 to culture solutions stimulated radish1 barley1 wheat and peas4 ,the intensity of the colour reaction of the oxidising enzyme of the manganese plants was found to exceed that of the control plants1 at least with regard to those leaves on the manganese plants which had turned a yellowish colour4 ,loew and ,sawa 7#aijb7 obtained an initial increase of growth with barley and soy beans in nutritive solutions #ja ferrous sulphate #jb manganese sulphate1 but this initial stimulation was followed by depression4 ,these authors support ,as's contention that manganese exerts both an injurious and a stimulative action upon plants1 and that the promoting effect is still observable with manganese compounds in high dilution1 while the injurious effects disappear under this condition4 ,the ,rothamsted experiments with barley show a decided stimulation with #a_/ajj1jjj ,mn,s,o and less4 ,care was taken to utilise sublimed ,fe,cl to avoid error due to the introduction of manganese into the control solution through the agency of this salt4 ,it is interesting to notice that concentrations that are weak enough to stimulate the vegetative growth still show a depressing action in that they retard the ripening of the grain1 a fact which supports ,loew and ,sawa's contention that manganese exerts both a toxic and a stimulative action at one and the same time1 the balance showing itself according to the concentration 7,fig4 #ag74 ,in the later experiments the plants were not allowed to form ears1 but similar results were obtained1 except that when dealing with the vegetative growth only1 a definite stimulus was obtained with a higher concentration than in those experiments in which the plants were allowed to form seed4 ,this may or may not be significant1 as it is possible that seasonal variation and individuality of the plants may have played some part4 ,barley seems to be most extraordinarily sensitive to the action of manganese1 as even #a part in #ajj1jjj1jjj was found to exercise a beneficial action 7,fig4 #ah74 ,with peas the evidence of stimulus is less well marked4 ,no sign of stimulation is obtained until a greater dilution is reached than is necessary with barley4 ,even so the resulting curves are not sufficiently conclusive to warrant the definite statement that manganese does act as a stimulant to peas when present in very small quantities 7,fig4 #ai74 ,illustration3 ,fig4 #ag4 ,curve showing the mean value of the dry weights of ten series of barley plants grown in the presence of manganese sulphate and nutrient salts4 7,feb4 #eth-,march #bith1 #aiji47 ,illustration3 ,fig4 #ah4 ,photograph showing the action of manganese sulphate on barley plants grown in the presence of nutrient salts4 7,feb4 #eth-,march #bith1 #aiji47 #a4 ,control4 #b4 #a_/aj1jjj manganese sulphate4 #c4 #a_/ajj1jjj #d4 #a_/a1jjj1jjj #e4 #a_/aj1jjj1jjj #f4 #a_/ajj1jjj1jjj ,illustration3 ,fig4 #ai4 ,photograph showing the action of manganese sulphate on pea plants in the presence of nutrient salts4 7,oct4 #bnd-,dec4 #bjth1 #aiab47 #a4 ,control4 #b4 #a_/e1jjj manganese sulphate4 #c4 #a_/aj1jjj #d4 #a_/be1jjj #e4 #a_/ej1jjj #f4 #a_/ajj1jjj #g4 #a_/bej1jjj #h4 #a_/ejj1jjj #i4 #a_/a1jjj1jjj 7b7 ,stimulation in soil cultures4 ,roxas carried out pot experiments with rice in soil to which was added varying proportions of manganese sulphate1 with and without the addition of nutrient salts of ammonium1 potassium1 and calcium4 ,the criterion of stimulation was the length of the growing leaves as measured daily1 a strength of ,m_/#ajjj ,mn,s,o 7,m molecular weight7 giving a favourable result4 ,in the ,hills ,experiments 7#aijc7 an increase of produce was obtained with wheat by manuring with manganese phosphate1 chloride1 sulphate1 or oxide 7,mn,o71 while an increase of straw was gained with nitrate1 though this compound decreased the yield of corn4 ,with barley no evidence of stimulation is set forth for any compound1 except that the root growth was improved by the addition of manganese iodide1 in spite of the general unfavourable action this substance exerted upon germination and growth4 ,bertrand 7#aije7 whose work will later be considered in detail1 experimented on arable land1 adding quantities of manganese sulphate 787 equivalent to about #af gm4 ,mn to each square metre1 growing oats from ,february to ,may4 ,increase of weight was found in the plants growing on the manganese plots1 the differences in favour of manganese being ,for total crops #bbe4 grain only #agd4 straw only #bfj4 ,a certain alteration in the quality of the grain was also noted from the manganese plots1 the weight per hectolitre exceeding that from the untreated plot1 the of water and of total nitrogen being somewhat lower than that from the untreated1 while the ash and the quantity of manganese present was the same in the grain from both plots4 ,bertrand suggested that these results might indicate a new line to follow in the study of the causes of the soil fertility4 ,strampelli 7#aijg7 tested the effect of manganese dioxide1 carbonate1 and sulphate1 and of a manganiferous mineral from the ,argentine upon wheat1 and found that while all four substances exercised a favourable influence on the vegetation1 the best result was obtained with the sulphate4 ,when however other manures were used in conjunction with the manganese compounds the balance of improvement shifted4 ,with nitrogen1 applied as nitrate of soda1 manganese dioxide proved the most beneficial1 with farmyard manure the manganiferous mineral#ad1 and with blood the carbonate4 ,it was also found that a manganese compost did not increase production when phosphatic manure was applied as basic slag4 #ad ,as no analysis of the mineral is given it is obviously impossible to say to what constituent the increase is due in this case4 ,feilitzen 7#aijg7 indicated that the nature of the soil plays its part in determining whether manganese acts as a stimulant or not4 ,his experiments were made in the field on poor moor soil1 which carried a little ,sphagnum turf and ,eriophorum1 and which was poor in food salts4 ,the soil was prepared and manured and then the plots were watered with a solution of #a gm4 ,mn,s,o4#d;,h,o per litre at the rate of #aj kgm4 sulphate per hectare1 six control plots being left untreated4 ,oats were sown and the soil rolled4 ,during growth no difference was noted between the various plots1 and after harvesting the weights of the different crops showed that the manganese had not caused increase of crop in either grain or straw on this poor moor soil4 ,the great bulk of the work on this problem has been carried out by various ,japanese investigators1 whose work extends over several years4 ,loew and ,sawa 7#aijb7 found that small quantities of manganese sulphate in soil cultures stimulated the growth of rice1 pea1 and cabbage4 ,they suggested that soils of great natural fertility contain manganese in an easily absorbed condition1 and that this forms one of the characteristics of such soils4 ,nagaoka 7#aijc7 dealt with plots in the rice fields which had not been manured for the three previous years and which were then treated with manure at the rate of #ajj kgm4 ammonium sulphate1 #ajj kgm4 potassium carbonate and #ajj kgm4 double superphosphate per hectare4 ,twelve series were worked in triplicate and received manganese sulphate in varying quantities1 equivalent to #j-ee kgm4 ,mn,o per hectare1 one set of three being left untreated4 ,the cultivation was normal and the application of manganese was found to influence the yield of rice4 #be kgm4 per hectare gave the best result and increased the harvest of grains by one-third2 higher doses of ,mn,o gave no better crop4 ,the percentage of grain relative to the straw was also increased4 ,the increase in both respects was evident all through the series from #aj to #ee kgm4 ,mn,o per hectare4 ,the conclusion was reached that the application of this salt to soils poor in manganese would be a commercial advantage4 ,the next year 7#aijd7 the experiments were extended to observe the after effects of the initial doses of manganese sulphate4 ,the harvest of grain was greatest in those plots that had received #cj kgm4 ,mn,o per hectare1 while it was approached very closely by that from the plot with #be kgm4 ,mn,o1 which had proved the best in the first year's experiments4 ,the maximum increase of yield over the unmanured plots in the first year was #cg1 while in the second year it dropped to #afi4 ,as 7#aijd7 also obtained an increase of one-third in produce of grain when #be kgm4 ,mn,o per hectare 7as manganous chloride7 was applied to rice4 ,the development of the plants was improved and the treated plants flowered about four days before the untreated ones4 ,loew and ,honda 7#aijd7 grew ,cryptomeria japonica in beds1 treating the soil with various manures and with iron or manganese sulphate4 ,the latter favoured increase in height1 and within #a years the cubic content of the trees had increased to double4 ,fukutome 7#aijd7 grew flax in pot cultures1 each pot containing #h kgm4 soil1 to which was added #d gm4 ,mn,cl4#d;,h,o and #d gm4 ,fe,s,o4#g;,h,o4 ,this mixture had a marked effect on the growth of the flax1 but the individual salts in doses of #d gm4 per #h kgm4 soil had but little effect4 ,namba 7#aijh7 applied manganese salts to onion plants in pots with a considerable measure of success4 ,pots containing #h kgm4 loamy soil were manured and received3 7#a7 no manganese1 7#b7 #a gm4 ,mn,s,o4#d;,h,o1 7#c7 #b gm4 ,mn,s,o4#d;,h,o1 the manganese sulphate being applied in high dilution as top dressing4 ,the bulbs and leaves were considerably stimulated by small doses of manganese sulphate1 the best results being obtained from 7#b71 which represents a manuring of #bb kgm4 ,mn,s,o per hectare4 ,an increase of the dose lessens the beneficial effect1 as the toxic action begins to come into play4 ,the actual figures obtained may prove of interest4 ,wt4 leaves ,wt4 bulbs ,total weight ,bulbs roots roots ,absolute ,relative leaves gm4 gm4 gm4 gm4 #a4 #bie #he #chj #ajjj #bh #b4 #chj #bbe #fje #aeib #ei #c4 #cee #afe #eaj #acdb #df ,uchiyama 7#aijg7 carried on a variety of experiments with manganese sulphate on several plants on different soils1 both in the field and in pots1 and found that the compound exercised a favourable action in most cases when applied in appropriate quantities4 ,in summarising his results he stated that both manganese and iron stimulate the development of plants1 different plants varying in their susceptibility to the action4 ,sometimes a joint application of the two salts is the most beneficial1 sometimes an individual application is the better1 in which case manganese sulphate is generally better than ferric sulphate in its action4 ,the stimulating action of manganese varies greatly with the character of the soil1 and the mode of application also affects results4 ,as a general rule the manganese acts best when applied as a top dressing rather than when added together with the manure4 ,further the stimulating action differs greatly with the nature and reaction of the manurial mixture4 ,uchiyama concludes that #bj-ej kgm4 per hectare of crystallised manganese sulphate is a good general amount to apply4 ,takeuchi 7#aiji7 corroborates the statements of the various writers that plants differ in their response to the manganese manuring4 ,pot cultures1 in each of which #h kgm4 soil were similarly manured1 received #b gm4 ,mn,s,o4#d;,h,o applied as a solution of #a_/ajj strength1 the controls receiving the same amount of water4 ,the manganese increased the green weight of spinach by #da1 while the dry weight of barley1 peas and flax rose #ec1 #aid1 and #aci respectively above that of the untreated4 ,the control plants of flax were behind the manganese plants in growth and flowering1 while barley was the least stimulated of all the test-plants4 ,other observations seemed to show that ,leguminosae and ,cruciferae are more susceptible to manganese stimulation than are the ,gramineae4 ,,iii4 ,,effect ,,of ,,manganese ,,compounds ,,on ,,certain ,,of ,,the ,,lower ,,plants4 ,the information on this point is exceedingly meagre1 possibly because of the diversion of general attention to the higher plants in view of the commercial interests involved4 ,richards 7#ahig7 carried out experiments with various nutritive media with the addition of certain metallic salts1 including those of zinc1 iron1 aluminium and manganese4 ,the fungi tested were ,aspergillus niger1 ,penicillium glaucum and ,botrytis cinerea4 ,his general conclusion was that fungi may be stimulated1 though it must not be concluded without further investigation that all fungi react in the same degree to the same reagent1 but this conclusion is traversed by ,loew and ,sawa 7#aijb74 ,these writers state that fungi are not stimulated by manganese1 and take this as a proof that the improvement in the growth of phanerogams1 induced by manganese compounds1 is not due to direct stimulation of the protoplasmic activity1 but to some other more obscure cause4 ,,iv4 ,,physiological ,,considerations ,,of ,,manganese ,,stimulation4 ,the physiological cause of the stimulation exerted by manganese compounds has raised much controversy4 ,loew and ,sawa suggested that the action of the sun's rays upon a normal plant puts a certain check on growth1 arising out of the action of certain noxious compounds which they supposed to be produced in the cells under the influence of light4 ,the stimulation of the manganese compounds may be due to a supposed increase in the oxidising powers of the oxidising enzymes1 so that destruction of the checking compounds can be accomplished as quickly as they are formed1 so enabling growth to continue more rapidly4 ,as 7#aijb7 had previously stated that colorimetric tests for oxidising enzymes indicate that the yellowish leaves from plants treated with manganese compounds give reactions of higher intensity than the green leaves from control plants1 the difference between the reactions being specially marked in barley1 and less so in radish4 ,bertrand has devoted much time to the consideration of this and allied problems4 ,in #ahig 7a1 b1 c7 he proceeded to investigate the essential nature of manganese in the economy of the plant1 his experiments showing its constant presence in a ferment 7laccase7 obtained from plants4 ,he also extracted from lucerne a substance very poor in manganese1 which was somewhat inactive1 but which regained or increased its activity on the addition of manganese4 ,bertrand stated that manganese was apparently not to be replaced by another metal1 not even by iron1 and that the small quantity of it occurring was no reason for regarding it as a secondary element in the composition of plants4 ,the view was also put forward that in the presence of certain organic substances1 such as hydroquinone1 pyrogallol or similar bodies1 manganese is capable of fixing free oxygen from the air1 the volume of oxygen absorbed varying according to the compound of manganese used4 ,bertrand was led to conceive the oxydases as special combinations of manganese in which the acid radicle1 probably protein in nature and variable according to the ferment considered1 would have just the necessary affinity to maintain the metal in solution1 i4e4 the form the most suitable for the part it has to play4 ,the manganese would then be1 according to his view1 the true active element of oxydase1 which functions as the 8activator02 the albuminous matter1 on the other hand1 gives to the ferment those special characters1 which show themselves in their behaviour with regard to reagents and physical agents4 ,from this point of view manganese could no longer be considered as a non-essential element1 but as a substance of vital necessity to the functions of plant-life4 ,the name 8complementary0 manure was suggested for compounds of such elements as manganese1 which exert a physiological action and which were proposed for use as manures4 ,later 7#aije7 ,bertrand considered that he had still further proved the indispensable nature of manganese4 ,the absence or insufficiency of one essential element arrests or diminishes growth4 ,this applies not only to those substances which are present in the greatest abundance1 such as ,c1 ,p1 ,n1 c41 but also to those elements like manganese1 boron1 and iodine1 which only occur in traces4 ,these elements are usually specialised in function1 and for them the name 8catalytic0 elements was suggested1 in view of the work they are held to do4 ,as late as #aiaj the rle of manganese in the functioning of the oxidising enzymes was again insisted on4 ,it was concluded that manganese intervenes as a catalytic agent in the material changes of which plants are the seat1 and that it participates in an indirect manner in the building up of the tissues and in the production of organic matter4 ,conclusion4 ,manganese exerts a toxic influence upon the higher plants1 if it is presented in high concentration1 but1 in the absence of great excess of the manganese compounds1 the poisoning effect is overshadowed by a definite stimulation4 ,as is the case with boron1 manganese stimulates some species more than others1 the action on barley being more evident than that on peas4 ,it seems probable that manganese may prove to be an element essential to the economy of plant life1 even though the quantity usually found in plants is very small4 ,,chapter ,,viii ,,conclusions ,in the foregoing chapters a very limited number of plant poisons have been considered1 yet there is sufficient evidence to show that even these few differ considerably in their action upon plant-life4 ,this action is most variable1 and it is impossible to foretell the effect of any substance upon vegetative growth without experiments4 ,the degree of toxicity of the different poisons is not the same1 and also one and the same poison varies in the intensity and nature of its action on different species of plants4 ,while certain compounds of copper1 zinc and arsenic are exceedingly poisonous1 compounds of manganese and boron are far less deleterious1 so that a plant can withstand the presence of far more of the latter substances than of the former4 ,again1 the tested compounds of copper1 zinc and arsenic do not seem to stimulate growth1 even when they are applied in the smallest quantities1 whereas very dilute solutions of manganese and boron compounds decidedly increase growth4 ,but1 differentiation occurs even in this stimulative action1 for while manganese is the more effective in stimulating barley1 boric acid is far more potent for peas1 the shoots being particularly improved4 ,a consideration of the experimental work that has been done on this subject of poisoning and stimulation leads one to the inevitable conclusion that it is not true to maintain the hypothesis that all inorganic plant poisons act as stimulants when they are present in very small quantities1 for while some poisons do increase plant growth under such conditions1 others fail to do so in any circumstances4 ,it is probable that what has been found true with the few substances tested would prove to be similarly true over a much wider range of poisons1 and at any rate the hypothesis must be dismissed in its universal application4 ,a more accurate statement would be that some inorganic poisons act as stimulants when present in small amounts1 the stimulating concentrations varying both with the poisons used and the plants on which they act4 ,it is quite possible for a stimulation in one respect to be correlated with a retardation in another4 ,in the ,rothamsted experiments on the action of manganese sulphate on barley the weaker concentrations of the salt improved the vegetative growth1 as was shown by the increase in the dry weights1 but with the same strengths of the poison the ripening of the grain was retarded1 so that1 while certain of the physiological functions were expedited1 others were hindered by the action of the poison4 ,thus it is evident that it is exceedingly difficult sharply to characterise either toxic or stimulant action4 ,in neither case is the reaction simple--many factors may come into play and many processes are concerned1 while the effect of a so-called poison may vary in respect of each of the functions and processes concerned4 ,if the poison is presented in great strength the toxic action is dominant1 and probably affects many functions in the same sense1 so that the action is1 so to speak1 cumulative4 ,lower down in the scale of concentration differentiation of action may set in1 and while some processes may still be hindered1 others may be stimulated4 ,if the two actions balance one another an apparent indifference may be manifested1 so that it seems that such strengths of the poison have no effect on growth1 either harmful or beneficial4 ,at still lower concentrations1 with certain plants and certain poisons1 the stimulative action overpowers the toxic effect1 so that in some respect or other improvement occurs in growth4 ,it is quite conceivable1 however1 that some poisons are truly indifferent in weak concentrations1 as no stimulation makes itself evident under any circumstances4 ,in these cases one is inclined to suspect that the action is somewhat more simple1 in that the toxic effects gradually diminish until no poisonous action is manifest at very weak concentrations1 and as no stimulation is present to bring the growth above the normal with these very weak concentrations the plant is similar to those grown without any addition of the poison4 ,the modus operandi of these stimulative agents is not yet fully understood4 ,perhaps at the present time two main theories hold the field3 7#a7 that they act as catalytic agents1 being valueless on their own account1 but valuable in that they aid in the procuring of essential food substances2 7#b7 that the stimulants themselves are of integral value for nutrition4 ,the ,french school1 with ,bertrand at the head1 hold strongly to the catalytic theory1 maintaining that manganese and boron compounds are able to increase growth if they are present in small quantities1 as they act as 8carriers0 whereby the various functions of the plant are expedited by the increased facility with which the essential nutritive elements are supplied4 ,the manganese in laccase1 for instance1 is held to be an oxygen carrier1 whereby the oxygen is first absorbed and then released for the benefit of the plant1 the manganese being regarded as essential for the functioning of the enzyme4 ,but1 if these elements are essential1 this theory seems to stop short of the truth4 ,if certain functions are dependent for their very occurrence upon the presence of even minute traces of any element1 then surely that element is as essentially a nutrient element1 as vital to the well-being of the plant as is such an element as carbon or nitrogen or phosphorus1 even though the latter occurs in far greater quantity4 ,it is necessary that one should free one's mind from the idea that the quantity of an element present in a plant is an index of its value to the plant4 ,naturally enough1 in the early days of plant physiology1 the most abundant elements first engaged the attention of investigators1 and they were divided into essential and non-essential1 ten elements being classed in the former category4 ,more recent work is beginning to show that other elements are constantly present in plants1 but in such small quantities that the older and cruder methods of analysis failed to reveal them1 so that until lately they have been completely overlooked in work on plant nutrition4 ,even yet we do not know which of these other elements are essential and which are merely accidental4 ,while we do know that the ten essential elements 7,c1 ,h1 ,o1 ,n1 ,s1 ,p1 ,k1 ,mg1 ,fe1 ,ca7 are necessary for the well-being of all plants1 it is conceivable that these other substances which only occur in very small quantities may be more individual in their action1 and that while a trace of a certain element may be absolutely essential to one plant1 that same element may be quite indifferent for another species4 ,if one takes a broad outlook1 the two theories seem to be in reality only parts of one1 the 8nutrition0 theory carrying matters a little farther than the 8catalytic0 idea1 broadening its scope and extending its application4 ,it seems probable that all the experimental work that has been discussed will prove to be simply preliminary to a far greater practical application of the principle of stimulation or increased growth4 ,while the physiologists have been feeling their way towards the conclusions put forth on this subject1 the agriculturists have been discovering and extending the application of artificial manures1 until at the present time such manuring is coming into its own and is receiving more of the widespread attention that it deserves4 ,the possibility now exists that in some respects the two lines of work are converging and that the more purely scientific line will have a big contribution to make to the strictly practical line4 ,artificial manuring aims at improvement of the soil and crop by the addition of food substances that are needed in a particular soil1 a result that used to be obtainable only by the use of the bulky farmyard manure1 seaweed1 c4 ,apart from any other aspect of the matter the artificials1 when intelligently used1 are far more easy to handle and to regulate in supply1 and they yield excellent results1 especially in conjunction with a certain proportion of organic manures4 ,the further prospect now opened up is the possibility of utilising some of these stimulating compounds as artificial manures4 ,as only small traces are beneficial1 larger amounts being poisonous1 it is obvious that only small quantities would be needed1 and1 as the compounds are not usually very expensive1 a considerable increase of crop for a relatively small outlay might be anticipated if no complicating factors intervened4 ,very much work will be required in the field to test the value of these substances1 as their action may be influenced by the nature of the soil1 climatic conditions1 general conditions of manuring1 and the crops grown4 ,some tests have already been made1 especially in ,japan1 with boron and manganese1 and these indicate a promising field for investigation4 ,above all1 it is most important to realise that one is approaching an entirely unexplored field1 and that it is inevitable that the results of the initial experiments will be contradictory1 at least in appearance1 so that it is necessary to keep an open mind on the subject1 being ready to modify one's ideas as circumstances require1 as improved experimental methods lead on to more accurate results4 ,,bibliography ,the references are to pages on which authors are mentioned4 ,papers to which no page-references are appended are not dealt with in the text4 ,,page ,,abba1 ,f4 ,ueber die ,feinheit der biologischen ,methode beim ,nachweis des ,arseniks4 ,centr4 ,bakt4 ,par4 ,abt4 #b1 ,,iv1 #hjf-h4 7#ahih7 #fc ,,aderhold1 ,r4 ,zur ,frage der ,wirkung des ,kupfers auf die ,pflanze4 ,ber4 ,deut4 bot4 ,gesell4 ,,xxiv1 #aab-h4 7#aijf7 -- ,,agulhon1 ,h4 ,recherches sur la prsence et le rle du bore chez les vgtaux4 ,thse4 ,paris4 7#aiaj a7 #fh1 #gj1 #gb1 #gc1 #gf ,,agulhon1 ,h4 ,accoutumance du mas au bore4 ,compt4 rend4 ,,cli1 #achb-c4 7#aiaj b7 #gb ,,agulhon1 ,h4 ,emploi du ,bore comme ,engrais catalytique4 #gth ,inter4 ,cong4 ,applied ,chem4 ,sect4 ,,vii1 ,agric4 ,chem4 #afe-f4 7#aiaj c7 #ga1 #gc ,,agulhon1 ,h4 ,emploi du bore comme engrais catalytique4 ,compt4 rend4 ,,cl1 #bhh-ia4 7#aiaj d7 #gc ,,amos1 ,a4 ,effect of fungicides upon the assimilation of carbon dioxide by green leaves4 ,journ4 ,agric4 ,sci4 ,,ii1 #beg-ff4 7#aijg-h7 #cc ,,andreasch1 ,r4 ,ueber die ,zusammensetzung der ,asche der ,gartennelke und der ,gartenrose4 ,journ4 prakt4 ,chem4 ,,xviii1 #bjd-g4 7#ahgh7 #gi ,,archangeli1 ,g4 ,sopra l'azione dell'acido borico sul germogliamento dei semi4 ,proc4 verb4 ,soc4 ,toscana sci4 nat4 ,pisa4 ,v1 #be-i4 7#ahhe7 #fg1 #gb ,,as1 ,k4 ,on the physiological influence of manganese compounds on plants4 ,bull4 ,coll4 ,agric4 ,tokyo1 ,v1 ,no4 #b1 #agg-he4 7#aijb7 #ha1 #hd1 #ij ,,as1 ,k4 ,on the practical application of manganous chloride in rice culture4 ,bull4 ,coll4 ,agric4 ,tokyo1 ,,vi1 ,no4 #b1 #aca-c4 7#aijd7 #hh ,,baker1 ,r4 ,t4 and ,,smith1 ,h4 ,g4 ,a ,research on the ,pines of ,australia4 7#aiaj7 #hj ,,baumann1 ,a4 ,das ,verhalten von ,zinksalzen gegen ,pflanzen und im ,boden4 ,landw4 ,versuchs-,stat4 ,,xxxi1 #a-ec4 7#ahhe7 #ci1 #db ,,baumann1 ,e4 ,ueber das normale ,vorkommen von ,iod im ,thierkrper4 ,zeitschr4 physiol4 ,chem4 ,,xxi1 #cai-ccj4 7#ahie7 #b ,,baumert1 ,g4 ,zur ,frage des normalen ,vorkommens der ,borsure im ,weine4 ,ber4 ,deut4 chem4 ,gesell4 ,,xxi1 #cbij-b4 7#ahhh7 #fe ,,bechi1 ,m4 ,e4 ,sur la prsence de l'acide borique dans les vgtaux4 ,bull4 ,soc4 ,chim4 ,paris1 ,,iii1 #abb4 7#ahij7 #ff ,,bechi1 ,e4 ,intorno alla diffusione dell'acido borico4 ,atti ,r4 ,accad4 ,econom4 ,agrar4 ,georgofili di ,firenze1 ,,xiv1 #bdj-ej4 7#ahia7 #ff ,,berlese und ,,sostegni4 ,untersuchungen ber die ,wirkung der ,kupfersalze auf die ,vegetation des ,weinstockes und auf den ,boden4 ,rev4 internat4 viticult4 et oenol4 7#ahie7 #bf ,,bertrand1 ,g4 ,sur l'intervention du manganse dans les oxydations provoques par la laccase4 ,compt4 rend4 ,,cxxiv1 #ajcb-e4 7#ahig a7 #ij ,,bertrand1 ,g4 ,sur l'action oxydante des sels manganeux et sur la constitution chimique des oxydases4 ,compt4 rend4 ,,cxxiv1 #acee-h4 7#ahig b7 #ij ,,bertrand1 ,g4 ,nouvelles recherches sur les ferments oxydants ou oxydases4 ,ann4 ,agronom4 ,,xxiii1 #che-ii4 7#ahig c7 #ij ,,bertrand1 ,g4 ,sur la recherche et sur l'existence de l'arsenic dans l'organisme4 ,ann4 ,inst4 ,pasteur1 ,,xvi1 #eec-fa4 7#aijb7 #ea ,,bertrand1 ,g4 ,les engrais complmentaires4 #eth ,internat4 ,kong4 angew4 ,chem4 ,berlin1 ,,iii1 #hci-dj4 7#aijc7 #ia ,,bertrand1 ,g4 ,sur l'emploi favorable du ,manganse comme engrais4 ,compt4 rend4 ,,cxli1 #abee-g4 7#aije7 #hf1 #ia ,,bertrand1 ,g4 ,sur les ,engrais catalytiques4 #gth ,internat4 ,cong4 ,applied ,chem4 ,sect4 ,,vii1 ,agric4 ,chem4 #aei-fb4 7#aiaj7 #ia ,,bokorny1 ,t4 ,uebereinstimmendes ,verhalten der ,metalle der ,kupfergruppe 7,kupfer1 ,quecksilber1 ,silber7 gegen ,zellen der niederen ,pflanzen4 ,chem4 ,zeit4 ,,xxix1 #b1 #abja-b4 7#aije7 #ce ,,bouilhac1 ,r4 ,influence de l'acide arsnique sur la vgtation des algues4 ,compt4 rend4 ,,cxix1 #ibi-ca4 7#ahid7 #fb ,,brand1 ,j4 ,die ,borsure1 ein steter ,begleiter des ,bieres und ein wesentlicher ,bestandtheil des ,hopfens4 ,zeitschr4 ges4 ,brauwesen1 ,,xv1 #dbf-h4 7#ahib7 #ff ,,breazeale1 ,j4 ,f4 ,effect of certain solids upon the growth of seedlings in water culture4 ,bot4 ,gaz4 ,,xli1 #ed-fc4 7#aijf7 #bc ,,brenchley1 ,w4 ,e4 ,the influence of copper sulphate and manganese sulphate upon the growth of barley4 ,ann4 ,bot4 ,,xxiv1 #ega-hc4 7#aiaj7 #bj1 #hb ,,brenchley1 ,w4 ,e4 ,on the action of certain compounds of zinc1 arsenic1 and boron on the growth of plants4 ,ann4 ,bot4 ,,xxviii1 #bhc-cja4 7#aiad7 #dj1 #df1 #ed ,,burlingham1 ,g4 ,s4 ,a study of the influence of magnesium sulphate on growth of seedlings4 ,journ4 ,amer4 ,chem4 ,soc4 ,,xxix1 #ajie-aab4 7#aijg7 #a ,,campani1 ,g4 ,il manganese nelle ceneri si manifesta facilmente sotto la forma di fosfato manganico4 ,gaz4 chim4 ital4 ,,vi1 #dfd-f4 7#ahgf7 #gi ,,campani1 ,g4 ,sull'esistenza del manganese nelle piante4 ,gaz4 chim4 ital4 ,,xiv1 #eae-f4 7#ahhd7 -- ,,cern1 ,k4 ,ueber das ,vorkommen von ,arsen im thierischen ,organismus4 ,zeitschr4 physiol4 ,chem4 ,,xxxiv1 #djh-af4 7#aija7 #ea ,,chatin1 ,a4 tudes de physiologie vgtale faites au moyen de l'acide arsnieux4 ,compt4 rend4 ,,xx1 #ba-i4 7#ahde7 #ea1 #eb1 #ei ,,chuard1 ,e4 et ,,porchet1 ,f4 ,l'action des sels de cuivre sur les vgtaux4 ,arch4 ,sci4 ,phys4 ,nat4 ,,xiv1 #ejb-e4 7#aijb7 #ca ,,chuard1 ,e4 et ,,porchet1 ,f4 ,l'action des sels de cuivre sur les vgtaux4 ,arch4 ,sci4 ,phys4 ,nat4 ,,xv1 #ia4 7#aijc7 #ca ,,colin1 ,h4 et ,,lavison1 ,j4 ,absorption compare des sels de ,baryum1 de ,strontium et de ,calcium par la plante vivante4 ,revue ,gn4 ,bot4 ,,xxii1 ,no4 #bfa1 #ccg-dd4 7#aiaj7 #e ,,collins1 ,s4 ,h4 ,the absorption of ,arsenic by ,barley4 ,journ4 ,soc4 ,chem4 ,ind4 ,,xxi1 #bba-b4 7#aijb7 #eb ,,copeland1 ,e4 ,b4 and ,,kahlenberg1 ,l4 ,the influence of the presence of pure metals upon plants4 ,trans4 ,acad4 ,sci4 ,arts and ,letters ,wisconsin1 ,,xii1 ,part #b1 #ded-gd4 7#aijj7 #ai ,,coupin1 ,h4 ,sur la toxicit des sels de cuivre l'gard des vgtaux suprieurs4 ,compt4 rend4 ,,cxxvii1 #djj-a4 7#ahih7 #ah ,,coupin1 ,h4 ,sur la nutrition du ,sterigmatocystis nigra4 ,compt4 rend4 ,,cxxxvi1 #cib-d4 7#aijc7 #di ,,crampton1 ,c4 ,a4 ,borsure als ,bestandtheil der ,pflanzen4 ,ber4 ,deut4 chem4 ,gesell4 ,,xxii1 #ajgb-f4 7#ahhi7 #fe ,,csapodi1 ,s4 ,das ,vegetiren der ,schimmelpilze auf festen ,arsenverbindungen4 ,bot4 ,centr4 ,,lvii1 #aja-b4 7#ahid7 #fc ,,dandeno1 ,j4 ,b4 ,an investigation into the effects of water and aqueous solutions of some of the common inorganic substances on foliage leaves4 ,trans4 ,canadian ,inst4 ,,vii1 #bcg-cej4 7#aijj-aijc7 #cb1 #dg ,,daubeny1 ,c4 ,memoir on the degree of selection exercised by plants1 with regard to the earthy constituents presented to their absorbing surfaces4 ,trans4 ,linn4 ,soc4 ,,xvii1 #bec-ff4 7#ahcc7 #e ,,daubeny1 ,c4 ,on the power ascribed to the roots of plants of rejecting poisonous or abnormal substances presented to them4 ,journ4 ,chem4 ,soc4 ,,xiv1 #bji-cj4 7#ahfb7 #e1 #eg ,,davy1 ,e4 ,presence of ,arsenic in plants cultivated for food4 ,gard4 ,chron4 ,sept4 #ajth1 #gci-dj4 7#ahei7 #ea1 #eh1 #fj ,,de ,,saussure4 ,recherches chimiques sur la vgtation4 ,paris4 7#ahjd7 #e1 #gh ,,dieulafait4 ,sur la prsence normale du cuivre dans les plantes qui vivent sur les roches de la formation primordiale4 ,compt4 rend4 ,,xc1 #gjc-e4 7#ahhj7 #ae ,,dubois1 ,r4 ,sur les moisissures du cuivre et du bronze4 ,compt4 rend4 ,,cxi1 #fee-g4 7#ahij7 #cc ,,dunnington1 ,f4 ,p4 ,manganese in the ,ash of ,wheat4 ,proc4 ,amer4 ,chem4 ,soc4 ,,ii1 #ada4 7#ahgh7 #gi ,,ehrenberg1 ,p4 ,wirkungen des ,zinks bei ,vegetationversuchen4 ,chem4 ,zeit4 ,,xxxii1 #icg4 7#aijh7 #dc ,,ewert1 ,dr4 ,der wechselseitige ,einfluss des ,lichtes und der ,kupferkalkbrhen auf den ,stoffwechsel der ,pflanze4 ,landw4 ,jahrb4 ,,xxxiv1 #bcc-caj4 7#aije7 #ca ,,feilitzen1 ,h4 von4 ,kann man auf dem freien ,felde einen gnstigen stimulierenden ,einfluss auf die ,entwickelung der ,kulturpflanzen durch kleine ,mengen ,mangansalze wahrnehmen8 ,journ4 ,landw4 ,,lv1 #bhi-ib4 7#aijg7 #hg ,,fitch1 ,r4 ,the action of insoluble substances in modifying the effect of deleterious agents upon the fungi4 ,ann4 ,mycologici1 ,,iv1 #cac-bb4 7#aijf7 #bc ,,fliche et ,,grandeau4 ,ann4 ,chim4 ,phys4 #ced4 7#ahgd7 #ga ,,frank1 ,b4 und ,,kr,,ger1 ,f4 ,ueber den ,reiz1 welchen die ,behandlung mit ,kupfer auf die ,kartoffelpflanze hervorbringt4 ,ber4 ,deut4 bot4 ,gesell4 ,,xii1 #h-aa4 7#ahid7 #cj ,,freytag1 ,m4 ,ueber den ,einfluss des ,zinkoxyds und seiner ,verbindungen auf die ,vegetation4 ,mitth4 ,knig4 landw4 ,akad4 ,poppelsdorf1 #hb-ii4 7#ahfh7 #cg1 #ch1 #db1 #dc ,,freytag1 ,m4 ,die schdlichen ,bestandteile des ,httenrauchs der ,kupfer-1 ,blei-1 und ,zinc-htten und ihre ,beseitigung4 ,landw4 ,jahrb4 ,,ii1 #cae-eg4 7#ahhb7 -- ,,fukutome1 ,t4 ,on the influence of manganese salts on ,flax4 ,bull4 ,coll4 ,agric4 ,tokyo1 ,,vi1 ,no4 #b1 #acg-h4 7#aijd7 #hh ,,gautier1 ,a4 et ,,clausmann1 ,p4 ,origines alimentaires de l'arsenic normal chez l'homme4 ,compt4 rend4 ,,cxxxix1 #aja-h4 7#aijd7 #ea ,,girard1 ,a4 ,sur l'accumulation dans le sol des composs cuivriques employs pour combattre les maladies parasitaires des plantes4 ,compt4 rend4 ,,cxx1 #aadg-eb4 7#ahie7 -- ,,gorup-,,besanez1 ,e4 von4 ,ueber das ,verhalten der vegetirenden ,pflanze und der ,ackererde gegen ,metallgifte4 ,ann4 ,chem4 ,pharm4 ,,cxxvii1 #bdc-ef4 7#ahfc7 #be1 #da1 #eh ,,gosio1 ,b4 ,einwirking von ,microphyten auf feste ,arsenverbindung4 ,mitt4 aus den ,lab4 sci4 della ,direzione di ,sanit4 ,abst4 in ,ber4 ,deut4 chem4 ,ges4 ,,xxv1 ,vol4 ,,iii1 #cdf4 7#ahib7 #fc ,,gosio1 ,b4 ,zur ,frage1 wodurch die ,giftigkeit arsenhaltiger ,tapeten bedingt wird4 ,ber4 ,deut4 chem4 ,gesell4 ,,xxx1 ,bd4 #a1 #ajbd-f4 7#ahig7 #fc ,,gosio1 ,b4 ,weitere ,untersuchungen ber die ,biologie und den ,chemismus von ,arsenschimmelpilzen4 ,il ,policlinico1 ,x4 7#aijj74 ,abs4 in ,bot4 ,centr4 ,,lxxxvii1 #aca-c4 7#aija7 #fc ,g,,ssl1 ,j4 ,ueber das ,vorkommen des ,mangans in der ,pflanze und ber seinen ,einfluss auf ,schimmelpilze4 ,beih4 ,bot4 ,centr4 ,,xviii1 #a1 #aai-cb4 7#aije7 #hj ,,guerin1 ,g4 ,sur un compos organique1 riche en manganse1 retir du tissu ligneux4 ,compt4 rend4 ,,cxxv1 #caa-b4 7#ahig7 #gi ,,gustavson1 ,g4 ,chemische ,rolle der ,mineralsalze in der organischen ,natur4 ,mitt4 ,landw4 ,forstwirthsch4 ,akad4 ,petrowsko-,rasumowsko4 ,heft #c1 #a-ae4 ,moskau4 7#ahha47 ,abst4 in ,just1 ,bot4 ,jahresber4 ,i1 #ch4 7#ahhb7 #de ,,guthrie1 ,f4 ,b4 and ,,cohen1 ,l4 ,note on the occurrence of manganese in soil and its effect on grass4 ,agric4 ,gaz4 ,new ,south ,wales1 ,,xxi1 #bai-bb4 7#aiaj7 #hc ,,guthrie1 ,f4 ,b4 and ,,helms1 ,r4 ,pot experiments to determine the limits of endurance of different farm crops to certain injurious substances4 ,part #a4 ,wheat4 ,ag4 ,gaz4 ,n4,s4,w4 ,,xiv1 #aad-bj4 7#aijc7 #fj ,,guthrie1 ,f4 ,b4 and ,,helms1 ,r4 ,ibid4 ,part #b4 ,maize4 ,ag4 ,gaz4 ,n4,s4,w4 ,,xv1 #bi-cb4 7#aijd7 #fj ,,guthrie1 ,f4 ,b4 and ,,helms1 ,r4 ,ibid4 ,part #c4 ,barley and ,rice4 ,part #d4 ,rye4 ,ag4 ,gaz4 ,n4,s4,w4 ,,xvi1 #hec-fj4 7#aije7 #fj ,,hall1 ,a4 ,d4 ,the ,book of the ,rothamsted ,experiments4 7#aije7 -- ,,hall1 ,a4 ,d41 ,,brenchley1 ,w4 ,e4 and ,,underwood1 ,l4 ,m4 ,the soil solution and the mineral constituents of the soil4 ,phil4 ,trans4 ,roy4 ,soc4 #bjd4 ,b4 #cjg4 #agi-bjj4 7#aiac7 #h ,,haselhoff1 ,e4 ,ueber die schdigende ,wirkung von kupfersulfat- und kupfernitrathaltigem ,wasser auf ,boden und ,pflanzen4 ,landw4 ,jahrb4 ,,xxi1 #bfc-gf4 7#ahib7 #be ,,haselhoff1 ,e4 ,versuche ber die ,einwirkung ,schwefliger ,sure1 ,zinkoxyd und ,zinksulfat auf ,boden und ,pflanzen4 ,ber4 ,versuchs-,stat4 ,marburg4 #aijc-d4 ,abst4 in ,jahresb4 ,agrik4 ,chem4 ,,vii1 #bfa4 7#aijd7 -- ,,hattensaur1 ,g4 ,zur chemischen ,zusammensetzung von ,molinia crulea ,mnch von ,knigsberg bei ,raibl4 ,ber4 ,kais4 ,akad4 ,wissens4 ,wien1 ,,xcix1 #b b4 #bi-ca4 7#ahia7 #af1 #cg ,,hattori1 ,h4 ,studien ber die ,einwirkung des ,kupfersulfats auf einige ,pflanzen4 ,journ4 ,coll4 ,sci4 ,tokyo1 ,,xv1 #cga-id4 7#aija7 #ca1 #cd ,,heald1 ,f4 ,d4 ,on the toxic effect of dilute solutions of acids and salts upon plants4 ,bot4 ,gaz4 ,,xxii1 #abe-ec4 7#ahif7 #bb ,,heckel1 ,e4 ,de l'action de quelques composs sur la germination des graines 7bromure de camphre1 borate1 silicate et arsniate de soude74 ,compt4 rend4 ,,lxxx1 #aagj-b4 7#ahge7 #fj1 #gb ,,herapath1 ,t4 ,j4 ,analyses of the ashes of some esculent vegetables4 ,quart4 ,journ4 ,chem4 ,soc4 ,,ii1 #d-bd4 7#ahdi7 #gh 8,,hills0 ,experiments4 ,influence of ,manganese salts on wheat and barley4 ,journ4 ,roy4 ,agric4 ,soc4 ,eng4 ,,lxiv1 #cdh-eg4 7#aijc7 #hc1 #hd1 #hf ,,hiltner1 ,l4 und ,,gentner1 ,g4 ,untersuchungen ber die ,ernhrungsverhltnisse unserer ,kulturpflanzen4 ,landw4 ,jahrb4 ,bayern4 ,no4 #aj1 pp4 #da-fb4 7#aiac7 #aj ,,holdefleiss4 7,discussion on zinc in soils and its effect on plant life47 ,landw4 ,versuchs-,stat4 ,,xxviii1 #dgb4 7#ahhc7 #db ,,hotter1 ,e4 ,ueber das ,vorkommen des ,bors im ,pflanzenreich und dessen physiologische ,bedeutung4 ,landw4 ,versuchs-,stat4 ,,xxxvii1 #dcg-eh4 7#ahij7 #fe1 #fg ,,hotter1 ,e4 ,ueber den ,borsuregehalt einiger ,obstarten4 ,zeitschr4 ,nahrungsmittel ,hyg4 ,war4 ,,ix1 #a-d4 7#ahie7 #fe ,,javillier1 ,m4 ,sur l'influence favorable de petites doses de zinc sur la vgtation de ,sterigmatocystis nigra ,v4 ,tgh4 ,compt4 rend4 ,,cxlv1 #abab-e4 7#aijg7 #di ,,javillier1 ,m4 ,sur la fixation du zinc par le ,sterigmatocystis nigra1 ,v4 ,tgh4 ,compt4 rend4 ,,cxlvi1 #cfe-g4 7#aijh a7 #di ,,javillier1 ,m4 ,le ,zinc chez les plantes4 ,recherches sur sa prsence et son rle4 ,ann4 ,inst4 ,pasteur1 ,,xxii1 #gbj-g4 7#aijh b7 #di ,,javillier1 ,m4 ,recherches sur la prsence et le rle du zinc chez les plantes4 ,thse4 ,paris4 7#aijh c7 #ch1 #dg ,,javillier1 ,m4 ,le ,zinc chez les plantes et son emploi comme ,engrais complmentaire4 #gth ,internat4 ,cong4 ,appl4 ,chem4 ,sect4 ,,vii1 ,agric4 ,chem4 #afc-d4 7#aiaj7 #df ,,javillier1 ,m4 ,sur la substitution au zinc de divers lments chimiques pour la culture du ,sterigmatocystis nigra4 ,compt4 rend4 ,,clv1 #aeea-b4 7#aiab7 -- ,,jay1 ,h4 ,sur la dispersion de l'acide borique dans la nature4 ,compt4 rend4 ,,cxxi1 #hif-i4 7#ahie7 #ff ,,jensch1 ,e4 ,beitrge zur ,galmeiflora von ,oberschlesien4 ,zeitschr4 angew4 ,chem4 #ad-e4 7#ahid7 #cg1 #dc ,,jensen1 ,g4 ,h4 ,toxic limits and stimulation effects of some salts and poisons on wheat4 ,bot4 ,gaz4 ,,xliii1 #aa-dd4 7#aijg7 #bd1 #ci1 #df ,,john1 ,j4 ,f4 ,chemische ,tabellen der ,pflanzen-analysen4 ,nrnberg4 7#ahad7 #gh ,,kahlenberg1 ,l4 and ,,true1 ,r4 ,h4 ,on the toxic action of dissolved salts and their electrolytic dissociation4 ,bot4 ,gaz4 ,,xxii1 #ha-abd4 7#ahif7 #ai1 #bb1 #fh ,,kanda1 ,m4 ,studien ber die ,reizwirkung einiger ,metallsalze auf das ,wachstum hheren ,pflanzen4 ,journ4 ,coll4 ,sci4 ,tokyo1 ,,xix1 ,art4 #ac1 #a-cg4 7#aijd7 #bh1 #df1 #dg ,,kane1 ,r4 ,researches on the composition and characters of certain soils and waters belonging to the flax districts of ,belgium and on the chemical constitution of the ashes of the ,flax plant4 ,proc4 ,roy4 ,dublin ,soc4 ,,lxxxiii1 #aec-agb4 7#ahdg7 #gh ,,kelley1 ,w4 ,p4 ,manganese in some of its relations to the growth of pineapples4 ,journ4 ,ind4 ,eng4 ,chem4 ,i1 #ecc-h4 7#aiji7 #hc ,,klopsch4 ,ueber die ,aufnahme von ,zink durch die ,pflanzen4 ,kulturtechniker1 #bbc-f4 7#aijh7 #ch1 #dg ,,knop1 ,w4 ,ueber die ,aufnahme verschiedener ,substanzen durch die ,pflanze1 welche nicht zu den ,nhrstoffen gehren4 ,jahresb4 ,agrik4 ,chem4 ,,vii1 #ach-dj4 7#ahhd7 #bd1 #ec1 #fb1 #fg1 #ha ,,krauch1 ,c4 ,ueber ,pflanzenvergiftungen4 ,journ4 ,landw4 ,,xxx1 #bga-ia4 7#ahhb7 #ci1 #dc ,,laband4 ,zur ,verbreitung des ,zinkes im ,pflanzenreiche4 ,zeitschr4 ,nahrungs- und ,genussmittel1 ,,iv1 #dhi-ib4 7#aija7 -- ,,lechartier1 ,g4 et ,,bellamy1 ,f4 ,sur la prsence du ,zinc dans le corps des animaux et dans les vgtaux4 ,compt4 rend4 ,,lxxxiv1 #fhg-ij4 7#ahgg7 #cg ,,leclerc1 ,m4 ,a4 ,dosage du manganse dans les sols et dans les vgtaux4 ,compt4 rend4 ,,lxxv1 #abji-ad4 7#ahgb7 -- ,,lehmann1 ,k4 ,b4 ,hygienische ,studien ber ,kupfer4 #a4 ,die ,bestimmung kleiner ,kupfermengen in organischen ,substanzen4 ,arch4 ,hyg4 ,,xxiv1 #a-hc4 7#ahie7 #af ,,lehmann1 ,k4 ,b4 ,ibid4 #d4 ,der ,kupfergehalt von ,pflanzen und ,thieren im kupferreichen ,gegenden4 ,arch4 ,hyg4 ,,xxvii1 #a-g4 7#ahif7 #af ,,le ,,renard4 ,du chmauxisme des sels de cuivre solubles sur le ,penicillium glaucum4 ,journ4 ,bot4 ,,xvi1 #ig-ajg4 7#aijb7 -- ,,liebig1 ,j4 ,die ,chemie in ihrer ,anwendung auf ,agricultur und ,physiologie4 7#ahdj7 #a ,,lindsay1 ,j4 ,the elimination of ,algae in lochs and ponds4 ,trans4 ,edinburgh ,field ,nat4 ,micros4 ,soc4 ,,vi1 ,part #e1 #dbb-ca4 7#aiac7 #ce ,,lippman1 ,e4 ,o4 von4 ,ueber einiger seltenere ,bestandtheile der ,rbenasche4 ,ber4 ,deut4 chem4 ,gesell4 ,,xxi1 #cdib-c4 7#ahhh7 #af1 #fe ,,loeb1 ,j4 ,the toxic and antitoxic effects of ions as a function of their valency and possibly their electrical discharge4 ,amer4 ,journ4 ,physiol4 ,,vi1 #daa-cc4 7#aijb7 #dd ,,loew1 ,o4 ,sind ,arsenverbindungen ,gift fr pflanzliches ,protoplasma8 ,pflger ,arch4 ,physiol4 ,,xxxii1 #aaa-c4 7#ahhc7 #fb ,,loew1 ,o4 ,bemerkung ber die ,giftwirkung des distillirten ,wassers4 ,landw4 ,jahrb4 ,,xx1 #bce4 7#ahia7 #aj ,,loew1 ,o4 ,ueber die physiologischen ,functionen der ,calcium- und ,magnesiumsalze im ,pflanzenorganismus4 ,flora1 ,,lxxv1 #cgd4 7#ahib7 #gf ,,loew1 ,o4 ,on the treatment of crops by stimulating compounds4 ,bull4 ,coll4 ,agric4 ,tokyo1 ,,vi1 ,no4 #b1 #afa-ge4 7#aijd7 -- ,,loew1 ,o4 ,,as1 ,k4 und ,,sawa1 ,s4 ,ueber die ,wirkung von ,manganverbindungen auf ,pflanzen4 ,flora1 ,,xci1 #bfd-gc4 7#aijb7 -- ,,loew1 ,o4 und ,,honda1 ,s4 ,ueber den ,einfluss des ,mangans auf ,waldbume4 ,bull4 ,coll4 ,agric4 ,tokyo1 ,,vi1 ,no4 #b1 #abe-cj4 7#aijd7 #gi1 #hh ,,loew1 ,o4 and ,,sawa1 ,s4 ,on the action of manganese compounds on plants4 ,bull4 ,coll4 ,agric4 ,tokyo1 ,v1 ,no4 #b1 #afa-gb4 7#aijb7 #ha1 #he1 #hg1 #ij ,,malaguti et ,,durocher4 ,sur la rpartition des lments inorganiques dans les principales familles du rgne vgtal4 ,ann4 ,chim4 ,phys4 ,,liv1 #beg-ig4 7#aheh7 #gh ,,maumen1 ,e4 ,j4 ,sur l'existence du manganse dans les plantes et son rle dans la vie animale4 ,bull4 ,soc4 ,chim4 ,paris1 ,,xlii1 #cje-ae4 7#ahhd7 #gi ,,mayer1 ,j4 ,e4 and ,,brazier1 ,j4 ,s4 ,analyses of mineral constituents of the ,flax plant1 and of the soils on which the plants had been grown4 ,quart4 ,journ4 ,chem4 ,soc4 ,,ii1 #gh-ij4 7#ahdi7 #gh ,,meissner1 ,w4 ,versuche ber den ,kupfergehalt einiger ,pflanzenaschen4 ,schweigger's ,journ4 ,chem4 ,phys4 ,,xvii1 #cdj-ed4 7#ahaf7 #ae ,,miani1 ,d4 ,ueber die ,einwirkung von ,kupfer auf des ,wachstum lebender ,pflanzenzellen4 ,ber4 ,deut4 bot4 ,gesell4 ,,xix1 #dfa-d4 7#aija7 #bh ,,micheels1 ,h4 ,sur les stimulants de la nutrition chez les plantes4 ,bull4 ,soc4 ,roy4 ,belgique1 ,,xlii1 ,part #b1 #bcc-i4 7#aijd-e7 #bg ,,micheels1 ,h4 ,influence de la valence des mtaux sur la toxicit de leur sels4 ,compt4 rend4 ,,cxliii1 #aaha-b4 7#aijf7 #dd ,,miyajima1 ,m4 ,on the poisonous action of ,copper upon various plants4 ,bot4 ,mag4 ,tokyo1 ,,xi1 #dag-bg 7#ahig74 ,ref4 in ,just's ,bot4 ,jahresb4 ,,ii1 #ahg-h4 7#ahih7 #bg ,,molisch1 ,h4 ,ueber lokale ,membranfrbung durch ,manganverbindungen bei einigen ,wasserpflanzen4 ,sitz4 ,kais4 ,ak4 ,wiss4 ,wien1 ,,cxviii1 #adbg-ci4 ,abst4 in ,knowledge1 ,,vii1 #ddh4 7#aiji7 -- ,,morel1 ,j4 ,action de l'acide borique sur la germination4 ,compt4 rend4 ,,cxiv1 #aca-c4 7#ahib7 #gb1 #gf ,,nagaoka1 ,m4 ,on the stimulating action of ,manganese upon ,rice1 ,i4 ,bull4 ,coll4 ,agric4 ,tokyo1 ,v1 ,no4 #d1 #dfg-gb4 7#aijc7 #hg ,,nagaoka1 ,m4 ,on the stimulating action of ,manganese upon ,rice1 ,,ii4 ,bull4 ,coll4 ,agric4 ,tokyo1 ,,vi1 ,no4 #b1 #ace-f4 7#aijd7 #hh ,n,,geli1 ,c4 ,ueber oligodynamische ,erscheinungen in lebenden ,zellen4 ,denkschr4 ,schweiz4 ,natur-gesell4 ,,xxxiii1 #a-dc4 7#ahic7 #bh ,,nakamura1 ,m4 ,can ,boric ,acid in high dilution exert a stimulant action on plants8 ,bull4 ,coll4 ,agric4 ,tokyo1 ,v1 ,no4 #d1 #eji-ab4 7#aijc7 #ga1 #gc ,,nakamura1 ,m4 ,can salts of ,zinc ,cobalt and ,nickel in high dilution exert a stimulant action on agricultural plants8 ,bull4 ,coll4 ,agric4 ,tokyo1 ,,vi1 ,no4 #b1 #adg-eb4 7#aijd7 #df ,,namba1 ,i4 ,on the behaviour of ,onion to stimulants4 ,bull4 ,coll4 ,agric4 ,tokyo1 ,,vii1 ,no4 #e1 #fce-f4 7#aijh7 #hc1 #hh ,,nazari1 ,v4 ,azione di alcune ossidasi artificiali e di diversi composti metallici1 sulla germinazione e sull'accrescimento delle piante4 ,staz4 sper4 agrar4 ,ital4 ,,xliii1 #ffg-hf4 7#aiaj7 #hd ,,nazari1 ,v4 ,influence of some artificial oxydases and some metallic compounds on the growth of wheat4 7#aiaj47 ,ref4 in ,exp4 ,stat4 ,rec4 ,,xxiv1 p4 #ecb4 7#aiaa7 #hd ,,nobbe1 ,f41 ,,baessler1 ,p4 und ,,will1 ,h4 ,untersuchungen ber die ,giftwirkung des ,arsens1 ,blei und ,zinc im pflanzlichen ,organismus4 ,landw4 ,versuchs-,stat4 ,,xxx1 #chj-dbc4 7#ahhd7 #dc1 #ec1 #ei ,,ono1 ,n4 ,ueber die ,wachstumbeschleunigung einiger ,algae und ,pilze durch chemische ,reize4 ,journ4 ,coll4 ,agric4 ,tokyo1 ,,xiii1 #ada-he4 7#aijj7 #cd1 #dh1 #fb1 #fc ,,orlowski1 ,s4 ,f4 ,ueber die ,wirkung des ,arsens auf das ,wachstum und die chemische ,zusammensetzung von ,aspergillus niger4 ,petersburg4 ,dissert4 7#aijb74 ,abst4 in ,biochem4 ,centr4 ,i1 #cbi4 7#aijb-c7 #fc ,,otto1 ,r4 ,untersuchungen ber das ,verhalten der ,pflanzenwurzeln gegen ,kupfersalzlsungen4 ,sorauer1 ,zeitsch4 ,pflanzenkrankh4 ,,iii1 #cbb-cd4 7#ahic7 #ag1 #bf ,,passerini1 ,n4 ,ricerche chimico-agricole sui ceci4 ,cicer arietinum ,l4 ,presenza del boro1 del litio e del rame nella pianta4 ,staz4 ,sper4 ,agrar4 ,ital4 ,,xxi1 #bj-cj4 7#ahia7 #af1 #ff ,,peligot1 ,e4 ,de l'action que l'acide borique et les borates exercent sur les vgtaux4 ,compt4 rend4 ,,lxxxiii1 #fhf-hh4 7#ahgf7 #ga ,,phillips1 ,f4 ,c4 ,the absorption of metallic oxides by plants4 ,chem4 ,news1 ,,xlvi1 #bbd-f4 7#ahhb7 #bd1 #db1 #ea1 #eh ,,phillips4 ,effets du cuivre sur la vgtation4 ,ann4 ,chim4 ,phys4 ,,xix1 #gf4 7#ahba7 #ae ,,raulin1 ,j4 tudes chimiques sur la vgtation4 ,ann4 ,sci4 ,nat4 ,,xi1 #aci-dj4 7#ahfi7 #dh ,,ricciardi1 ,l4 ,sulla diffusione dell'allumina nei vegetali4 ,gaz4 chim4 ,ital4 ,,xix1 #aej-i4 7#ahhi7 #gi ,,richards1 ,h4 ,m4 ,die ,beeinflussung des ,wachstums einiger ,pilze durch chemische ,reize4 ,jahrb4 wiss4 ,bot4 ,,xxx1 #ffe-hh4 7#ahig7 #ej1 #ij ,,richter1 ,a4 ,zur ,frage der chemischen ,reizmittel4 ,die ,rolle des ,zinc und ,kupfer bei der ,ernhrung von ,aspergillus niger4 ,centr4 ,bakt4 ,par4 ,abt4 #b1 ,,vii1 #dag-bi4 7#aija7 #cd1 #di ,,risse1 ,h4 ,quoted in ,sachs 8,experimental-,physiologie der ,pflanzen40 #aec-d4 7#ahfe7 #cf ,,roxas1 ,m4 ,the effect of some stimulants upon rice4 ,philippine ,agric4 and ,forester1 ,i1 ,no4 #e1 #hi-ig #dg1 #hf ,,salm ,,horstmar1 ,prince de4 ,recherches sur la nutrition de l'avoine1 particulirement en ce qui concerne les matires inorganiques qui sont ncessaires cette nutrition4 ,ann4 ,chim4 ,phys4 ,,xxxii1 #dfa-ejg4 7#ahea7 #hb ,,schlagdenhauffen et ,,reeb4 ,sur les combinaisons organiques des mtaux dans les plantes4 ,compt4 rend4 ,,cxxxix1 #ihj-c4 7#aijd7 #gi ,,schreiner1 ,o4 and ,,reed1 ,h4 ,s4 ,power of ,sodium ,nitrate and ,calcium ,carbonate to decrease toxicity in conjunction with plants growing in solution cultures4 ,journ4 ,amer4 ,chem4 ,soc4 ,,xxx1 #he-ig4 7#aijh7 #d ,,schr,,der1 ,j4 etc4 ,chemische ,zusammensetzung der ,pflanze4 ,a4 ,anorganische ,bestandtheile4 ,jahresber4 ,agrik4 ,chem4 #aje et seq4 7#ahgh7 #hj ,,segale1 ,m4 ,untersuchungen ber das ,vorhandensein von ,arsen in den normalen ,geweben vermittelst der biologischen ,methode4 ,zeitschr4 physiol4 ,chem4 ,,xlii1 #age-hj4 7#aijd7 #fc ,,seynes1 ,m4 ,j4 de4 ,rsultats de la culture du ,penicillium cupricum ,trabut4 ,bot4 ,soc4 ,france1 ,,xlii1 #dea-e4 7#ahie7 #cd ,,stoklasa1 ,j4 ,ueber die ,bedeutung des ,arsens in der ,pflanzenproduction4 ,casopis pro prumysl chemicky1 #e1 #caa1 #cgi1 #djg 7#ahie74 #f1 #ahb 7#ahif74 ,abst4 in ,jahresb4 ,agrik4 ,chem4 ,,xix1 #bdf-g4 7#ahif7 #ec1 #fj ,,stoklasa1 ,j4 ,ueber die physiologische ,bedeutung des ,arsens im ,pflanzenorganismus4 ,zeitschr4 landw4 ,versuchswes4 ,oesterreich1 ,i1 #aee-ic4 7#ahih7 #ec1 #eg1 #eh1 #fj ,,storp1 ,f4 ,ueber den ,einfluss von ,kochsalz- und ,zincsulfathaltigen ,wasser auf ,boden und ,pflanzen4 ,landw4 ,jahrb4 ,,xii1 #gie-hdd4 7#ahhc7 #dj1 #db1 #dc1 #dd ,,strampelli1 ,n4 ,azione del diversi composti di manganese ed in particolare del minerale manganesifero del ,monte ,argentario1 usati nella concimazione delle piante4 #f ,cong4 internat4 ,chim4 appl4 ,roma1 ,,iv1 #ad-g4 7#aijg7 #hg ,,swain1 ,r4 ,e4 and ,,harkins1 ,w4 ,d4 ,arsenic in vegetation exposed to smelter smoke4 ,journ4 ,amer4 ,chem4 ,soc4 ,,xxx1 #iae-bh4 7#aijh7 #eb ,,takeuchi1 ,t4 ,on differences of susceptibility of plants to stimulation4 ,journ4 ,coll4 ,agric4 ,tokyo1 ,i1 ,no4 #b1 #bjg-aj4 7#aiji7 #hi ,,trabut1 ,m4 ,l4 ,sur un ,penicillium vgtant dans des solutions concentres de sulfate de cuivre4 ,bull4 ,soc4 ,bot4 ,france1 ,,xlii1 #cc-d4 7#ahie7 #cd ,,treboux1 ,o4 ,einige stoffliche ,einflsse auf die ,kohlensureassimilation bei submersen ,pflanzen4 ,flora1 ,,xcii1 #ef-h4 7#aijc7 #cb1 #dh ,,true1 ,r4 ,h4 and ,,gies1 ,w4 ,j4 ,on the physiological action of some of the heavy metals in mixed solutions4 ,bull4 ,torr4 ,bot4 ,club1 ,,xxx1 #cij-djb4 7#aijc7 #bj1 #dj1 #de ,,true1 ,r4 ,h4 and ,,oglevee1 ,c4 ,s4 ,the effect of the presence of insoluble substances on the toxic actions of poisons4 ,science1 ,,xix1 #dba-d4 7#aijd7 #bb ,,true1 ,r4 ,h4 and ,,oglevee1 ,c4 ,s4 ,the effect of the presence of insoluble substances on the toxic action of poisons4 ,bot4 ,gaz4 ,,xxxix1 #a-ba4 7#aije7 #bb ,,uchiyama1 ,s4 ,influence of stimulating compounds upon the crops under different conditions4 ,bull4 ,imp4 ,cent4 ,agric4 ,expt4 ,stat4 ,japan1 ,i1 ,no4 #b1 #cg-gi4 7#aijg7 #hi ,,underwood1 ,l4 ,m4 vide ,,hall1 ,,brenchley and ,,underwood #h ,,vedr,,di1 ,v4 ,das ,kupfer als ,bestandtheil der ,sandbden und unserer ,culturgewchse4 ,chem4 ,zeit4 ,,xvii1 #aicb4 7#ahic7 #af ,,vedr,,di1 ,v4 ,das ,kupfer als ,bestandtheil unserer ,vegetabilien4 ,chem4 ,zeit4 ,,xx1 #cii-djj4 7#ahif7 #ag ,,verschaffelt1 ,e4 ,mesure de l'action des poisons sur les plantes4 ,archiv4 ,nerland4 ,sci4 ,exact4 ,nat4 ,haarlem1 ,x1 #a-g4 7#aije7 #bf ,,warden1 ,c4 ,j4 ,h4 ,analysis of ,behar ,opium ash4 ,chem4 ,news1 ,,xxxviii1 #adf4 7#ahgh7 #gi ,,wehmer1 ,c4 ,pflanzenstoffe4 7#aiaa7 #eb ,,wieler1 ,a4 ,die ,wirkung metallischer ,gifte im ,boden auf das ,pflanzenwachstum4 ,pflanzenwachstum und ,kalkmangel im ,boden1 #agg-bce4 7#aiab7 -- ,,wittstein1 ,dr und ,,apoiger1 ,f4 ,entdeckung der ,borsure im ,pflanzenreiche4 ,ann4 ,chem4 ,pharm4 ,,ciii1 #cfb-fd4 7#aheg7 #fe ,,wolff1 ,e4 ,aschen-analysen von landwirtschaftlichen ,producten1 ,fabrikabfllen und wildwachsenden ,pflanzen4 ,berlin4 7#ahga7 #gh ,,index ,,of ,,plant-,,names ,the symbols after the plant-names represent the elements referred to on the pages indicated4 ,acorus ,calamus ,mn1 #gi ,actinostrobus pyramidalis ,mn1 #hj ,aesculus ,mn1 #gh ,agathis robusta ,mn1 #hj ,ageratum ,cu1 #bd2 ,zn1 #db ,alder ,as1 #ec ,algae ,as1 #fb1 #fd2 ,b1 #ff1 #gg ,allium 7see ,onion7 ,zn1 #dg ,alnus incana ,mn1 #gi ,aloe ,cu1 #bf ,amomum sp4 7,paradieskrner7 ,cu1 #ae ,ampelopsis ,cu1 #cb2 ,zn1 #dg ,anaboena ,cu1 #ce ,angiosperms ,b1 #ff ,anthracnose ,b1 #gf ,apple ,b1 #fe1 #ff ,apricot ,cu1 #af ,araucaria ,bidwilli ,mn1 #hj ,cunninghamii ,mn1 #hj ,armeria sp4 ,zn1 #ch vulgaris ,zn1 #cf1 #cg ,arundo ,sacchar ,mn1 #gh ,asparagus ,mn1 #gi ,aspergillus ,cu1 #cc1 #cd ,aspergillus niger 7 ,sterigmatocystis nigra7 ,zn1 #dh1 #di1 #ej2 ,as1 #fc2 ,b1 #gf2 ,mn1 #ij ,athrotaxis selaginoides ,mn1 #hj ,barley1 #aa1 #ac2 ,sr1 #e2 ,cu1 #af1 #ag1 #bj1 #bi2 ,zn1 #cg1 #ci1 #dj1 #dd1 #df2 ,as1 #eb1 #ed1 #ee1 #eg1 #fj1 #fa2 ,b1 #ff1 #fi1 #ge2 ,mn1 #gi1 #ha1 #hb1 #hc1 #hd1 #he1 #hf1 #hi1 #ij1 #ib1 #ic1 #id ,beans ,cu1 #af1 #ag1 #bf2 ,zn1 #dg ,beech ,mn1 #gi ,beetroot 7,beta vulgaris7 ,cu1 #af1 #bf2 ,zn1 #cg1 #ci2 ,mn1 #gh1 #gi ,beet1 sugar ,b1 #fe ,betula alba ,b1 #ff ,birch ,mn1 #gi ,botrytis cinerea ,mn1 #ij ,brassica oleracea ,mn1 #gh ,buckwheat1 #aa2 ,cu1 #af1 #ag1 #bi1 #cj2 ,as1 #ec 7see ,polygonum ,fagopyrum7 ,cabbage ,sr1 #e2 ,as1 #ea1 #eb2 ,mn1 #hg ,cacao ,cu1 #af ,callitris gracilis ,mn1 #hj robusta ,mn1 #hj ,cannabis ,b1 #gb sativa ,b1 #ff ,capsella ,bursa-pastoris ,zn1 #cg ,cardamomum minus ,cu1 #ae ,carrot ,mn1 #gi ,cauliflower ,mn1 #gh ,cherry ,b1 #fe ,chestnut ,ca1 #ga2 ,mn1 #gi ,chickpea ,cu1 #af2 ,b1 #ff ,chicory ,mn1 #gi ,chrysanthemum ,b1 #ff ,clover ,zn1 #db1 #dd ,colea ,cu1 #bd2 ,zn1 #db2 ,as1 #eh ,collinsia ,b1 #gb ,coniferae ,zn1 #ch ,conium maculatum ,mn1 #gh ,colza ,b1 #gd ,couch grass ,mn1 #hc ,cow pea ,cu1 #ah ,cruciferae ,mn1 #gh1 #hi ,cryptomeria japonica ,mn1 #hh ,curcuma longa ,cu1 #ae ,currant ,cu1 #ca ,dacrydium ,franklini ,mn1 #hj ,dianthus caryophyllus ,mn1 #gi ,elodea canadensis ,cu1 #cb2 ,zn1 #dh ,fagopyrum esculentum ,cu1 #bi ,ferns ,b1 #ff ,fig ,zn1 #db2 ,b1 #fe1 #ff ,fir ,mn1 #hj ,flax ,mn1 #gh1 #hh1 #hi ,fungi ,cu1 #cc2 ,zn1 #dd1 #ej2 ,as1 #fd2 ,b1 #ff1 #gg ,geranium ,cu1 #bd2 ,zn1 #db2 ,as1 #eh ,gramineae ,b1 #gb2 ,mn1 #hi ,grasses ,zn1 #ci1 #dj1 #db ,gymnosperms ,b1 #ff2 ,mn1 #hj ,haricot ,b1 #ga1 #gb green ,as1 #eb white ,zn1 #cg ,hemp ,sr1 #e ,hop ,b1 #ff ,hordeum distichum ,as1 #ed vulgare ,zn1 #ci1 #dg 7see ,barley7 ,iberis ,b1 #gb ,laminaria saccharina ,b1 #ff ,leguminosae ,b1 #gb2 ,mn1 #gh1 #hi ,lentil ,mn1 #gi ,lichen ,as1 #ei ,linseed ,cu1 #af1 #ag ,linum ,b1 #gb ,love-apple ,b1 #ff ,lucerne ,mn1 #gi1 #ia ,lupin ,cu1 #ag1 #ai2 ,as1 #ei white ,as1 #fa2 ,b1 #fg1 #gj 7see ,lupinus albus7 yellow ,b1 #gj1 #ge ,lupinus albus ,cu1 #ai1 #bj1 #bb2 ,zn1 #de2 ,b1 #fh 7see ,white ,lupin7 ,maasa picta ,b1 #fe ,maize ,cu1 #af1 #ag1 #ai1 #bd1 #bf1 #bg2 ,zn1 #cg1 #dd2 ,as1 #ec1 #ed1 #fj2 ,b1 #fg1 #fh1 #ga1 #gb1 #gd2 ,mn1 #gi1 #ha ,menyanthes trifoliata ,cu1 #ce ,mildew ,b1 #gf ,molinia crulea ,cu1 #af2 ,zn1 #cg ,mould ,b1 #gf ,mucor mucedo ,as1 #ei1 #fc ,mushroom ,b1 #ff ,mustard ,cu1 #ag ,nasturtium ,cu1 #ag ,nuphar lutea ,cu1 #ce ,oak ,cu1 #af2 ,zn1 #db ,oat ,cu1 #af1 #ag1 #ai2 ,as1 #ec2 ,b1 #gd2 ,mn1 #gi1 #hb1 #hf1 #hg ,onion ,b1 #ff2 ,mn1 #hh ,onobrychis sativa ,zn1 #ci ,opium ,mn1 #gi ,oscillatoria ,cu1 #ce ,panicum italicum ,cu1 #bf2 ,as1 #eh ,pansy ,cu1 #bd2 ,zn1 #db2 ,as1 #eh ,paprika ,cu1 #af1 #ag ,paradieskrner 7,amomum sp47 ,cu1 #ae ,pea 7see ,pisum sativum7 sweet ,cu1 #ag ,pear ,cu1 #af2 ,b1 #fe ,penicillium ,cu1 #cc1 #cd brevicaule ,as1 #fc cupricum ,cu1 #cd glaucum ,cu1 #bc2 ,as1 #ei1 #fc2 ,mn1 #ij ,phaseolus vulgaris ,cu1 #ag2 ,as1 #ei ,phormidium ,valderianum ,as1 #fb ,phyllocladus rhomboidalis ,mn1 #hj ,pine ,mn1 #hj ,pineapple ,mn1 #hc ,pisum arvense ,cu1 #bi sativum ,cu1 #ag1 #ah1 #bf1 #bg1 #bi2 ,zn1 #da1 #dg2 ,as1 #eh 78,pea071 #c1 #aa1 #ac1 #ic2 ,cu1 #ag1 #bf1 #bi1 #cj2 ,zn1 #dj1 #df2 ,as1 #ea1 #ed1 #ee1 #ef1 #eh1 #fa2 ,b1 #fg1 #gc1 #gd1 #ge1 #ic2 ,mn1 #gi1 #ha1 #hb1 #he1 #hf1 #hg1 #hi1 #ib ,plantago lanceolata ,zn1 #cg ,podocarpus elata ,mn1 #hj ,polygonum amphibium ,cu1 #ce aviculare ,zn1 #cg1 #ch ,fagopyrum ,cu1 #bf1 #ci2 ,zn1 #da2 ,as1 #ed1 #eh 7see ,buckwheat7 ,persecaria ,cu1 #e2 ,as1 #ed ,poplar ,cu1 #ae ,potato ,cu1 #af1 #bf1 #bg1 #cj2 ,as1 #eb2 ,mn1 #gh1 #gi ,protococcus infusionum ,as1 #fb sp4 ,as1 #fc ,pyrus communis ,mn1 #gi ,radish ,sr1 #e2 ,b1 #gd2 ,mn1 #hd1 #ij ,raphanus ,b1 #gb sativus ,zn1 #ci ,raspberry ,as1 #fe ,rice ,zn1 #dg2 ,b1 #ff1 #gc2 ,mn1 #gi1 #hf1 #hg1 #hh ,rosa remontana ,mn1 #gi ,rubus ,b1 #ff ,rye ,cu1 #af2 ,as1 #fj1 #fa ,sainfoin ,mn1 #gi ,secale cereale ,cu1 #bf2 ,zn1 #da2 ,as1 #eh ,silene inflata ,zn1 #cf1 #cg ,solanum tuberosum ,mn1 #gh ,soy beans ,cu1 #ag1 #ai2 ,b1 #fg2 ,mn1 #ha1 #he ,spinach1 #da2 ,b1 #gc2 ,mn1 #hi ,spergula arvensis ,zn1 #ci ,spirogyra ,cu1 #ce2 ,as1 #fb2 ,b1 #gf ,stichococcus bacillaris ,as1 #fb ,sterigmatocystis nigra ,zn1 #dh1 #di 7see ,aspergillus niger7 ,sugar cane ,b1 #fe ,taraxacum officinale ,zn1 #cg ,tea ,mn1 #gi ,thlaspi alpestre ,zn1 #cf sp4 ,zn1 #ch ,tobacco ,b1 #ff ,trapa natans ,mn1 #gi ,trifolium pratense ,zn1 #ci ,triticum vulgare ,cu1 #ag2 ,b1 #fg 7see ,wheat7 ,tropeolum ,lobbianum ,cu1 #ag1 #ah ,turnip ,as1 #ea1 #eb2 ,b1 #gd swede ,mn1 #gh ,tussilago ,farfara ,zn1 #cg1 #ch ,ulothrix tenerrima ,as1 #fb ,ustilago ,cu1 #bh ,vaucheria ,b1 #gf ,vicia ,faba ,sr1 #e2 ,cu1 #bg1 #bi sativa ,b1 #fg2 ,zn1 #ci ,viola sp4 ,zn1 #ch tricolor ,zn1 #cf ,vine ,cu1 #ca ,vitis vinifera ,as1 #eb ,watercress ,b1 #ff ,water-melon ,b1 #fe ,wheat ,cu1 #af1 #ag1 #bc2 ,zn1 #cg1 #dd1 #df2 ,as1 #eb1 #fj2 ,b1 #ff1 #gj1 #gb1 #gc2 ,mn1 #gi1 #ha1 #hc1 #hd1 #he1 #hf1 #hg ,willow ,zn1 #ci1 #dj ,yeast ,zn1 #ej2 ,b1 #gf ,zea japonica ,cu1 #ag1 #ah ,mays 7see ,maize7 ,,general ,,index ,absorption capacity of soils for zinc1 #da of poisons by plants1 #be ,accelerators1 #de ,action of heavy metals in mixed solutions1 #bj ,adsorption1 #h1 #bc ,aeration in water cultures1 #h ,algae1 assimilation of arsenic by1 #fb clearing ponds of1 #ce effect of arsenic on1 #fb effect of boron on1 #gf effect of copper on1 #ce ,aluminium1 #de1 #gh ,arbutin1 #d ,arsenate1 potassium1 #ec1 #fb1 #fc sodium1 #ee1 #eg1 #fa ,arsenates1 #ec1 #eg ,arsenic acid1 #ec1 #ed1 #fj1 #fa1 #fb1 #fd acid v4 arsenious acid1 #ec acid v4 phosphoric acid1 #ec1 #fb elimination of1 #ei gas liberated by moulds1 #fc in soil1 effect of1 #eh in superphosphate1 #eh ,arsenious acid1 #ec1 #ed1 #eg-fa1 #fd immunity of plants to1 #eh ,arsenite1 sodium1 #ee1 #ef1 #fa ,arsenites1 #ec1 #eg v4 arsenates1 #eg ,artificial oxydases1 #hd soil1 #bd1 #df ,assimilation1 reduction in water plants1 #dh ,barium1 #dd ,borate1 calcium1 #ga potassium1 #ga ,borates1 #gb ,borax1 #ga1 #gc ,bordeaux mixture1 #cj blocking of stomata by1 #cc on assimilation1 effect of1 #cc ,boric acid1 #a1 #fe-gf1 #ic ,boromannitic acid1 #fh ,boron1 antiseptic action of1 #gj colour due to1 #ge distribution in plants1 #ff poisoning1 indication of1 #fh1 #fi rle in plant economy1 #gd ,cadmium1 #ca ,calamine1 #cg plants1 #ch soils1 flora of1 #cg ,calcium carbonate1 #d1 #bc1 #be chloride1 #bj1 #ei sulphate1 #bj1 #dd1 #de ,carbon black1 #bc dust1 #aj ,catalytic elements1 #di1 #ia ,chlorophyll1 #dd1 #fj ,complementary manures1 #dg1 #ia ,conditions of plant life1 #g ,copper1 acetate1 #ai action on plant organs1 #cj bicarbonate1 #bf bromide1 #ai chloride1 #ai1 #bj compounds1 corrosive action on plant roots1 #e1 #bg distribution in tissues1 #af mode of action on plants1 #be nitrate1 #ai1 #be oxide1 #ae1 #be quantity in certain plants1 #ag salts1 injection into plant tissue1 #ca sprays1 effect on leaves1 #cj1 #cb sulphate1 #e1 #ai1 #bj1 #bb-bg1 #bi-ce1 #da ,cumarin1 #d ,distilled water1 preparation of1 #aj ,double decomposition in soil1 #be ,duration of experiments1 #ac ,experimental methods1 comparison of1 #ad ,ferric chloride1 sublimed1 #hf hydrate1 #bc ,fungi1 effect of arsenic on1 #fc effect of boron on1 #gf effect of copper on1 #cc1 #cd effect of manganese on1 #ij effect of zinc on1 #dh ,galactose1 #gf ,glucose1 #gf ,germination1 effect of arsenic on1 #fj effect of boron on1 #gb effect of copper on1 #bg1 #bh effect of manganese on1 #hd effect of zinc on1 #dc of seeds in sawdust1 #aa ,grading of seeds1 #aa ,growth in copper-distilled water1 #ag of peas in water cultures1 #aa ,hydrochloric acid1 #bb ,hydroquinone1 #ia ,hypothesis of universal stimulation1 #ic ,iodine1 #b1 #ia ,individuality of plants1 error due to1 #ac of species1 #fa ,interaction between soil and poison1 #i ,iron1 #ca1 #di oxide1 #gh sesquioxide1 #hd sulphate1 #dh1 #ha1 #he1 #hh ,laccase1 #ia1 #ie ,lack of control over field experiments1 #i ,lead1 #aj1 #bf1 #db1 #dd ,magnesium carbonate1 #hc1 #hd1 #hg chloride1 #bj sulphate1 #a ,manganese as top-dressing1 #hi chloride1 #hf1 #hh commercial value of1 #hh cytological action of1 #ha1 #hb dioxide1 #hd1 #hg essential to ,coniferae1 #hj in ,australian soils1 #hc in leaves1 deposition of1 #hb in organic combination1 #gi iodide1 #hc1 #hd manuring1 after-effects of1 #hh nitrate1 #hc1 #hd oxide1 #gh1 #gi1 #hc1 #hd1 #hf1 #hh phosphate1 #gi1 #hc1 #hf retardation of ripening by1 #hb1 #he sulphate1 #ha-hi1 #id ,masking effect of inorganic food salts1 #d1 #bj ,mercuric chloride1 #bb oxide1 #da ,mercury1 #bf ,metallic oxides1 #gh ,methods2 field experiments1 #i sand cultures1 #h soil cultures in pots1 #i water cultures1 #g1 #aa ,mode of entry of poisons into plants1 #d ,nickel1 #bd1 #ej ,nucleinic combination1 #gi ,nutrient solutions1 composition1 #ac ,oligodynamic action1 #bh ,over-mineralisation of plants1 #ga ,phosphoric acid1 #ec1 #ed1 #fb1 #fd ,photo-synthesis1 effect of copper on1 #cb ,potassium hydrate1 #bb ,presence of arsenic in animals1 #ea in plants1 #ea of boron in plants1 #fe of copper in plants1 #ae of manganese in plants1 #gh of zinc in plants1 #cf ,pyrogallol1 #ia ,raulin's solution1 #di ,reproduction of poisoned plants1 #dj ,silver nitrate1 #bb ,sodium chloride1 #bj1 #dd hydroxide1 #bb nitrate1 #d ,sterile cultures1 #bd ,stimulation1 by injection of copper solutions1 #ca by small doses of poisons1 #b definition of1 #b local1 #dg of ,aspergillus niger1 #ej of fungi by copper1 #cd of plants by arsenic1 #fa of plants by boron1 #gc of plants by copper 7negative71 #bh of plants by manganese1 #hd of plants by zinc1 #de-dg physiological considerations of manganese1 #ij ,strontium sulphate1 #e ,sugar1 #bb1 #ca1 #dh1 #di1 #ej1 #fh ,sulphur1 flowers of1 #aj ,thymol1 #bb ,toxic action1 effect of arsenic1 #eb effect of boron1 #fg effect of copper1 #ag effect of light on1 #dd effect of manganese1 #ha effect of zinc1 #ch equivalent1 #ah limits of plant poisons1 estimation of1 #bf ,toxicity1 of nutrient salts1 #a of organic compounds1 #d of poisons1 cause of1 #bb of positive ions in copper compounds1 #ai1 #bb reduction of1 #ci1 #dd reduction of1 by carbon black and ferric hydrate1 #bc reduction of1 by insoluble substances1 #bb ,toxin and nutrient1 distinction between1 #c ,transmission of power of resistance1 #gb ,valency1 effect on toxicity1 #dd ,vanillin1 #d ,variation in results on different substrata1 #bd ,zinc1 absorption by roots1 #db carbonate1 #ch1 #db1 #dc effect of1 on lower plants1 #dh effect of1 on plant and soil1 #da fixation of1 #di mode of action on plants1 #dc oxide1 #cg1 #dg oxide on leaves1 deposition of1 #dg storage in seeds1 #dc sulphate1 #ch-di sulphide1 #db ,,cambridge3 ,,printed ,,by ,,john ,,clay1 ,m4,a4 ,,at ,,the ,,university ,,press4 ,,cambridge ,,agricultural ,,monographs ,,general ,,editors3 ,t4 ,b4 ,,wood1 ,m4,a41 ,draper's ,professor of ,agriculture in the ,university of ,cambridge1 and ,e4 ,j4 ,,russell1 ,d4,sc41 ,director of the ,rothamsted ,experimental ,station1 ,harpenden1 ,herts4 ,each volume of this series will contain a summary of the present position on some particular aspect or branch of agricultural science by an expert of acknowledged authority4 ,the treatment will be critical and impartial1 and sufficiently detailed on all points of fundamental importance to be of use alike to all readers1 but especially to those who are not in touch with an institution possessing a well equipped reference library4 ,full references will be given1 and a bibliography attached for the benefit of those who wish to follow up any particular point4 ,the following volumes are in preparation3 ,the ,strength of ,wheat ,flour4 ,by ,professor ,t4 ,b4 ,,wood1 ,m4,a4 ,the ,constitution of the ,soil4 ,by ,e4 ,j4 ,,russell1 ,d4,sc4 ,disease ,resistance4 ,by ,r4 ,h4 ,,biffen1 ,m4,a41 ,f4,r4,s41 ,professor of ,agricultural ,botany in the ,university of ,cambridge4 ,poisonous ,plants4 ,by ,h4 ,c4 ,,long4 ,,the ,,cambridge ,,farm ,,institute ,,series ,,general ,,editors3 ,professor ,t4 ,b4 ,,wood1 ,m4,a41 and ,e4 ,j4 ,,russell1 ,d4,sc4 ,the volumes of this series are intended to meet the needs of the many ,farm ,institutes already in existence or about to be formed4 ,they are intended for the average student whose object is to farm1 rather than for the exceptional man who wishes to become an agricultural expert4 ,every endeavour will be made to attain a high standard educationally1 by training students to take an intelligent interest in their daily work and to appreciate the beauty of the common objects among which their life will be passed4 ,on the other hand the fact that farm students must earn their living on the land will not be lost sight of4 ,the following will be among the first volumes3 ,farm ,accounts4 ,by ,c4 ,s4 ,,orwin4 ,now ready ,plant ,life in ,farm and ,garden4 ,by ,professor ,r4 ,h4 ,,biffen1 ,m4,a4 ,the ,feeding of ,farm ,animals4 ,by ,professor ,t4 ,b4 ,,wood1 ,m4,a4 ,a ,student's ,book about ,soils and ,fertilizers4 ,by ,e4 ,j4 ,,russell1 ,d4,sc4 ,common ,fungus and ,insect ,foes4 ,by ,f4 ,r4 ,,petherbridge1 ,m4,a4 ,,selection ,,from ,,the ,,general ,,catalogue ,,of ,,books ,,published ,,by ,,the ,,cambridge ,,university ,,press ,,the ,,cambridge ,,british ,,flora ,by ,c4 ,e4 ,,moss1 ,d4,sc41 ,f4,l4,s41 assisted by specialists in certain genera4 ,illustrated from drawings by ,e4 ,w4 ,,hunnybun4 ,the work will be completed in about ten volumes4 ,volume ,,ii is now ready4 ,the styles of binding and the prices will be as follows3 ,published ,price ,price per volume per volume to subscribers to the whole work ,paper boards1 with canvas back and paper label1 each volume in two parts1 the first containing the text and the second the plates #b #ajs net #b #es net ,quarter morocco1 in two parts divided as above #f net #e #es net ,paper boards1 with canvas back and paper label1 in one volume1 the plates mounted on guards and bound interspersed with the text #c net #b #aes net ,quarter morocco1 in one volume1 the plates mounted on guards and bound interspersed with the text #f net #e #es net 8,the appearance of ,dr ,moss's work has been anticipated by ,british botanists with the greatest interest2 not only to them does it appeal1 for its completeness and attention to detail entitle it to rank among works of ,continental importance4 ,the ,cambridge ,university ,press has been fortunate in securing the services of ,dr ,moss1 than whom no one more competent for the task could be found4 ,by a combination as admirable as it is rare1 ,dr ,moss is at once an acute field botanist1 a diligent investigator of herbaria1 and a student of botanical literature4444 ,mr ,hunnybun's drawings are all made from living plants1 so that the work may be regarded as representing more fully than has been hitherto done our knowledge of ,british ,botany at the present day40--,journal of ,botany4 ,genera of ,british ,plants4 ,arranged according to ,engler's ,syllabus ,der ,pflanzenfamilien 7,seventh edition #aiab71 with the addition of the ,characters of the ,genera4 ,by ,h4 ,g4 ,,carter1 ,m4,b41 ,ch4,b4 ,crown #hvo4 #ds net4 ,british ,rust ,fungi 7,uredinales74 ,their ,biology and ,classification4 ,by ,w4 ,b4 ,,grove1 ,m4,a4 ,demy #hvo4 ,with #bij figures4 #ads net4 ,types of ,british ,vegetation4 ,by members of the ,central ,committee for the ,survey and ,study of ,british ,vegetation4 ,edited by ,a4 ,g4 ,,tansley1 ,m4,a41 ,f4,l4,s4 ,crown #hvo4 ,with #cf plates and #ba figures4 #fs net4 ,the ,production and ,utilisation of ,pine ,timber in ,great ,britain4 ,part ,i4 ,production4 ,by ,e4 ,r4 ,,burdon1 ,m4,a41 and ,a4 ,p4 ,,long1 ,b4,a4 ,no4 #a4 ,sample ,plots of ,scots ,pine at ,woburn4 ,demy #hvo4 ,paper covers4 #as #f;d net4 ,no4 #b4 ,sample ,plot of ,scots ,pine at ,king's ,lynn4 ,demy #hvo4 ,paper covers4 #i;d net4 ,the ,journal of ,agricultural ,science4 ,edited by ,r4 ,h4 ,,biffen1 ,m4,a41 ,f4,r4,s41 ,a4 ,d4 ,,hall1 ,m4,a41 ,f4,r4,s41 ,e4 ,j4 ,,russell1 ,d4,sc41 and ,t4 ,b4 ,,wood1 ,m4,a4 ,vols4 ,i1 ,,ii1 ,,iii1 ,,iv and ,v now ready4 ,in four parts4 ,paper covers4 #aes net per volume4 ,bound in ,buckram1 #ahs #f;d net per volume4 ,price to subscribers1 #aes net per volume1 post free1 payable in advance4 ,the price of each part sold separately will be #es net4 ,cambridge ,university ,press ,c4 ,f4 ,clay1 ,manager3 ,fetter ,lane1 ,london 99 99 99 99 99 ,transcriber's ,notes ,minor inconsistencies in punctuation have been standardised--in particular1 missing periods and parentheses have been supplied where obviously required4 ,all other original errors and inconsistencies have been retained1 except as follows3 ,page #bg3 changed ,just to ,just's 7in ,just's ,bot4 ,jahresber47 ,page #cg3 ,added missing decimal point 7total ash1 7#jjf of the7 ,page #gf3 changed gms4 to gm4 7in until #e gm4 boric7 ,page #ig3 changed in to im 7,vorkommen von ,iod im ,thierkrper47 ,page #ih3 changed and to et 7,colin1 ,h4 et ,lavison1 ,j47 ,page #ajj3 changed ,experiments to experiments 7,pot experiments to determine the7 ,page #aja3 changed crulea to crulea 7,zusammensetzung von ,molinia crulea7 ,page #aja3 changed and to und 7,hiltner1 ,l4 und ,gentner1 ,g47 ,page #aja3 changed ,waar4 to ,war4 7,nahrungsmittel ,hyg4 ,war4 ,,ix1 #a-d47 ,page #ajb3 changed ,genuss-mittel to ,genusmittel 7,nahrungs- und ,genussmittel17 ,page #ajb3 added date to entry 7,,iv1 #dhi-ib4 7#aija77 ,page #ajb3 changed ,rbensache to ,rbenasche 7,bestandtheile der ,rbenasche4 ,ber47 ,page #ajc3 changed ,magenesium-salze to ,magnesiumsalze 7,calcium- und ,magnesiumsalze im7 ,page #aje3 changed ,vorhandsein to ,vorhandensein 7das ,vorhandensein von ,arsen7 ,page #aje3 changed ,pflanzen-production to ,pflanzenproduction 7der ,pflanzenproduction4 ,casopis pro7 ,page #aje3 changed prumsyl to prumysl 7,casopis pro prumysl chemicky17 ,page #ajg3 added entry for ,cu under ,fungi 7,cu1 #cc27 ,page #aaj3 changed ,photosynthesis to ,photo-synthesis 7,photo-synthesis1 effect of copper on1 #cb7