AGRICULTURAL CHEMISTRY AND VEGETABLEPHYSIOLOGY.THE record of the year includes no notable discovery nor anypaper that is likely to be reckoned in the future as of fundamentalimportance ; in several directions, however, good progress has beenmade, although, as the subject opens up, it is only to disclose itsincreasing complexity. Agricultural chemistry is essentially aborder-line science, dwelling on the confines of chemistry andphysics, botany, and physiology alike, touching these subjects alsojust where they are most difficult and obscure. The chemistry of thegrowing plant and of the feeding animal is the chemistry of theproteins and the carbohydrates, of enzyme action, and of the variedfunctions of the cell, whilst the study of the soil a t once leadsto some of the most difficult problems of solution, and of the inter-action of molecular and chemical forces which take place in thethin films surrounding the soil particles.So&? Bacteriology.Considering first the soil, the part played by the organismscontained therein assumes every year a greater importance; i tbecomes increasingly evident that plant production in the openfield, and the effect of fertilisers and even of cultivation, aredetermined by the nature of the soil flora and the repression orencouragement of particular groups of micro-organisms.The freeorganisms in the soil that can fix atmospheric nitrogen continuet o receive considerable attention, and the chief conditions of theiractivity-a supply of oxidisable carbohydrate, from which theymay derive the necessary energy, and the presence of calciumcarbonate to neutralise the acids produced-may be regarded asestablished; i t is the magnitude of the part played by Azotobacterand its congeners, under natural conditions, that remains to bedetermined.A. Koch and his colleagues a t Gottingenl showthat the addition of dextrose, sucrose, soluble starch, or straw tosoil brings about an increase in the amount of nitrogen i t contains;Absh., 1908, ii, 56262 ANN'IJAL REPORTS ON THE PROGRESS OF CHEMISTRY.the best effect was obtained by a single application of 2 per cent.of dextrose, when 8 to 10 milligrams of nitrogen were fixedfor each gram of sugar added. They also showed that the nitrogencompounds formed by the Azotobacter, the chief organism con-cerned, were easily nitrified; as a consequence, when sugar wasadded to soil in pots in which successive crops of oats andbuckwheat or sugar beet were grown, the nitrogen fixation induced bythe sugar became evident in an increased yield.The first crop of oatswas reduced, the unchanged sugar acting injuriously on the growingplant, but in the following year the yield of buckwheat or beet wasmuch increased, being nearly trebled where 4 per cent. of sugar hadbeen added. A t the end of the experiment, the sugar-treated soilwas also found to have been enriched in nitrogen. That the depres-sion of the first crop was due to the injurious effect of the unalteredsugar was shown by another experiment, in which the soil, afterthe addition of the sugar solution, was kept in an incubator forfour weeks.Oats were then sown, which yielded more than doublethe amount of dry matter that was obtained in the check experi-ments, where the soil received no sugar. These experiments con-stitute the first direct experimental demonstration that A zotobact ercan play a practical part in provision of nutriment for the higherplants.H. R. Christensen2 has dealt with the importance of calciumcarbonate and the phosphates in the nutrition of Azotobacter.He showed that the occurrence of Azotobacter in various soilsstands in close relationship to the amount of calcium carbonatein the soil, exceptionally active soils always possessing an alkalinereaction, which confirms the observations of S.F. Ashby on theRothamsted soils.3 He even considers that the growth of Azoto-bacter will form the most trustworthy evidence that can be obtainedof the presence of traces of calcium carbonate in soils. J. F.Lipman 4 also used A zotobact er as a test of the state of the mineralconstituents of the soil, and reaches much the same conclusionsas Christensen, whilst Wilfarth and Wimmer found thepresence of phosphoric acid essential.As regards fixation of nitrogen by the nodule organisms of theleguminosze, no new step can be reported; various preparations ofthe organism are being widely used* in a practical way for theinoculation of seed or soil before a leguminous crop, although thebest way of preserving the cultures in an active condition hasCentr.Bctkt. Par., 1907, 11, 17, 109, 161, 378, 735.Rpport New Jersey Agric. Exp. Station, 1907.See Remy, Centr. Bakt, Par., 1907, 11, 17? 661,9 J. Agrie. Sci., 1907, 2, 35.Abstr., 1907, ii, 809AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 263not yet been settled? But, although inoculations may be of thegreatest possible benefit in introducing the appropriate organisminto soils which have never previously carried the leguminouscrop in question, such soils are exceptional, and it is not yetdemonstrated that there is any return for the ihoculation ofordinary cultivated land, It is uncertain whether more activeraces of the clover organism, for example, can be distinguished,and, further, i t is uncertain if such improved races, when intro-duced into ordinary soil swarming with kindred organisms, cansurvive the competition that results, so as to produce any permanenteffect upon the crop.As regards nitrification, perhaps the most important of thebacterial processes in the soil, Kaserers reports the isolation ofanother bacterium, B.nitrator, which forms nitrates from ammoniain a single operation. Hitherto, no nitrifying organisms havebeen detected other than those first distinguished by Waringtonand then isolated and described by Winogradsky, Nitrosmonas andNitroscoccus, which oxidise ammonia t o nitrite, and the Nitro-bacter, which completes the change t o nitrate. Muntz and Lain6 9have been studying the nitrification process on a large scale toascertain if the old nitre beds could be so far improved as t obecome practical sources of nitrate, supposing the conditions ofa century ago were to recur and France were again cut off fromany external supply of Chilian or Indian nitrate.Miintz obtainedthe most intensive nitrification when a weak solution of ammoniumsulphate percolated through a layer of some medium offering alarge surface, peat proving the most effective when an excess ofcalcium carbonate was maintained. The inhibiting effect oforganic matter on nitrification does not hold for the humic com-pounds of peat. A strong solution of ammonium sulphate cannotbe nitrified, but by repeatedly adding further small amounts toa solution that has already been oxidised, and passing it againthrough a nitrifying bed, the concentration of the calcium nitratecould at last be raised to about 44 per cent.Some little time wasnecessary before the beds reached this efficiency, since the nitri-fying organisms only gradually become habituated to working insolutions of such a concentration. In view of the rapid develop-ment of the electrical processes for making nitrates, it is -improb.able that Miintz’s improved nitre beds will ever be required.Perhaps the most interesting question in soil bacteriology whichhas of late been opened up, is concerned with the increased pro-ductiveness shown by soil that has been subjected to some processR. G. Smith, Ahstr., 1907, ii, 498.Bull. Soc. d’encourugeinent pour 2’Industrie Nntionnte, 190’1, 109, 951.8 Ibid., 381264 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRP.of partial sterilisation, such its heating to the temperature ofboiling water, or treatment with volatile antiseptics like carbondisulphide o r toluene.The facts have been disclosed in a moreor less accidental fashion by various workers during the last tenyears or so, 'but it is only just lately that they have attractedmuch attention, or have been seen to possess any general signifi-cance. Various papers on the \subject appeared during 1907(Heinze,lo Kochll), including one by F. V. Darbishire and E. J.Russell,l2 which traverses the whole ground very thoroughly. I ncontinuance of the work of these authors on the rate of oxicla-tion in soiIs,13 they were led to observe that soils which had beenheated to looo, or treated for a time with volatile antiseptics,always showed a higher rate of oxidation than the same soilsuntreated. As they had previously established an interdependencebetween the rate of oxidation and the fertility of a soil, theyproceeded to test the effect of such treatment upon the productive-ness of soils by means of experiments in pots.The soils were eitherheated for two or three hours to a temperature of 90-95O, or treatedin their pots for about a week with a small quantity of carbondisulphide, toluene, or chloroform, after which they were spreadout in thin layers until all trace of the antiseptic had volatilised;no trace of the antiseptic could be detected by any of the teststhen applied. Various crops were grown in the pots, and in allcases the treated soil yielded a greater weight of dry matterthan the untreated soil, the increase being generally from 10t o 40 per cent., but occasionally as high as 70 to 90 per cent.The beneficial effect of the treatment was also seen when a secondcrop was taken without further disturbance of the soil, but itdid not extend t o the third crop.Not only was the dry matterincreased, but it was, as a rule, richer in nitrogen, phosphoricacid, and potash, so that the crop always removed larger amountsof these fundamental nutrients from the treated soil.The result of heating the soil was even more marked; exceptin the case of certain leguminous plants, the yield of the heatedsoil was generally doubled or even trebled, and again the effectpersisted to the second, and sometimes to further crops.It is impossible to explain these results from a purely chemicalpoint of view, for, even if the heating might be supposed to rendermore available the store of plant food in the soil, no correspondingaction could be attributed to the vapour of toluene or chloroform.It was demonstrated that the soils were not completely sterilisedby the treatment, and the mold tenable explanation is that theAbstr., 1907, ii, 388, 502, 572.11 B i d . , 647.13 Ann, Report, 1905, 251. $2 J, Agric. Sci., 1907, 2, 305AGRICULTURAT~ CHEMISTRY AND VEGETABLE PHYSIOLOGY. 265partial sterilisation exercises some selective action on the groupso l bacteria in the soil, destroying some which are unfavourable tothe growth of the plant, and thereby giving other beneficial forms,like the oxidising bacteria, a greater scope.One of Darbishire andRussell’s experiments is rather significant in this connexion ; theyfound that if they watered the heated soil with ordinary well-water,i t lost some of its superiority over the untreated soil, thus indicatingthat the beneficial rearrangement of the original soil flora broughtabout by the partial sterilisation can only persist when the soilis watered with sterile water introducing no new forms.With this work of Darbishire and Russell’s may be connectedan investigation by 0. Rahn 14 on the effect that drying soil a t theordinary temperature has on its bacteriological properties.Soilwhich had merely been aIlowed to dry was found to induce greaterbacteriological changes, as, for example, production of acid in dex-trose solutions, production of carbon dioxide in sugar solution con-taining calcium carbonate, formation of ammonia in urea orpeptone solutions, than did the same soil after storage in a moistcondition. These effects were most manifest with a rich gardensoil, but it was not settled whether they were to be regardedas accelerations due to drying, or depressions brought about bystorage in a moist state. The number of the bacteria (growingupon gelatine) in the soil was always diminished by drying, andthe author considers that his results show the effects were due tosome substance formed in the soil by drying, which is soluble, notdecomposed by boiling its solution, and not of the nature of anordinary plant nutrient.Experiments on the effect of a pre-liminary drying of the soil on mustard in pots were not conclusive.The susceptibility of the soil to changes of this kind is a questionstill open to a good deal of elucidation, but i t already promisesresults which may attain considerable practical importance ; mean-time, it also serves to emphasise the necessity for caution in draw-ing conclusions from any experiments on soil, when what is appar-ently so small a disturbance can bring about such a radical changein its productiveness.Sod Ch emistry.I n this section of our subjkct there is nothing novel to report,although Whitney and his colleagues of the Division of Soils(U.S. Department of Agriculture) have issued several bulletins,l5in which they continue t o develop their somewhat remarkabletheory of the functions of soil and fertilisers, a theory which hasl4 Cmtr.Bakt. Par., 1607, 11, 20, 38.l5 See particularly Eulletias Nos. 36, 40, qnd 47266 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY,found no acceptance, nor much consideration, among Europeanchemists .I6Briefly, Whitney’s theory is that soils become infertile throughthe accumulation of toxic substances excreted by the roots of crops,and that fertilisers act, not by directly feeding the plant, butby in some way destroying or putting out of action these toxicexcretions. The experiments brought forward in support of thistheory are chiefly made with wheat seedlings in water cultures,the seedlings being from six to twenty days old, and thereforestill drawing their nutriment from the endosperm.The reportsgo to show that the growth of such seedlings in distilled wateris injured by the addition of an aqueous extract of certain soils,but that the injurious effect of the extract can be removed by a pre-liminary filtration through finely-divided carbon, shaking up withferric hydroxide or calcium carbonate, and, as a rule, by boiling.Other experiments showed that water in which such seedlings havebeen grown for a time acts injuriously on the growth of a newbatch of seedlings, but that filtration through carbon, &c., as before,restores the water in which the seedlings have been grown to anormal condition suitable for renewed growth.Distilled watercontaining very small amounts of such plant products as neurine,guanidine, coumarin was also shown t o be hurtful t o the develop-ment of the seedlings, but was again improved by the treatmentdescribed before. Many questions suggest themselves in readingthese interesting reports and the speculations they give rise to, butcriticism is as yet impossible; the data supplied afford no means ofestimating the magnitude of the experimental error, which is knownto be great in experiments of this kind, and the experiments them-selves are never pushed to the point of becoming really critical ofthe theory, the authors seeming to be content to multiply results(( which may be explained by supposing,” o r are ‘( in accord with theassumption upon which the experiment was made.” Here, in Europe,we must suspend our judgment until we receive a more criticalversion of the work.The perennial question of the most suitable solvent to use forthe determination of the ((available” mineral plant food in thesoil continues to receive attention.E. A. Mitscherlich 17 selectedwater saturated with carbon dioxide, which substance he regardsas the main secretion of the plant’s roots, and the effective solventunder ordinary soil conditions (see also Stoklasa, dzc.18). He thenproceeded systematically t o the examination of one or two soilswith the view of determining the effect of the concentration ofl6 See, however, Pouget and Chouchak, Compt.rend., 1907, 145, 1200.l7 Landw, Jahrbucher, 1907, 36, 309, l8 Abstr., 1907, ii, 717ACXRICULTURATA CHEMISTRY AND VEGETART,F, PHYSIOLOGY. 267the carbon dioxide in the solution, of the duration of the action,and of temperature, so as to arrive at the probable error attachingt o estimations of this method. It is noteworthy that the tem-perature factor is considerable for the potash and nitrogen, butnot for phosphoric acid or lime, although it has hitherto beenneglected in considering these various methods of extraction ofweak solvents. No attempt was made by Mitscherlich to corre-late his results with the behaviour of the soils in the field; this,however, was the prime object of A. de Sigmond,lD who has exam-ined Hungarian soils by an entirely different method.de Sigmondstarted from some experiments of Schloesing’s,20 who showed thatil a series of samples of soil be attacked by very dilute solutionsof nitric acid, the strength of which increases by steps, the amountof phosphoric acid dissolved increases at first with the strengthof the nitric acid solution, then remains constant for a time, and thenbegins to rise again. This second increase, according t o Schloesing,marks the point a t which the nitric acid becomes more than strongenough to dissolve all the ‘‘ available ” phosphoric acid, so thatit then begins to attack the more insoluble compounds presentin the soil. de Sigmond generally discusses the results obtainedby this method, which was thus tried for the first tJme on a largescale, and obtained a considerable agreement between them andthe behaviour of the soils towards phosphatic fertilisers, as judgedby a series of field and pot experiments, which are also reported.Another question which dates back to the earliest days of agri-cultural chemistry, the withdrawal of ammonia from its com-pounds, and its retention by the soil, has been re-examined duringthe year by A.D. Hall and C. T. Gimingham.21 These authorsfound that the action was always one of double decomposition,either with the zeolitic double silicates of the soil, ammoniumbeing withdrawn and an equivalent amount of calcium, mag-nesium, potassium, or sodium taking its place in the solu-tion, or with humus (calcium humate), in which case anequivalent amount of calcium again replaced ammonium in thesolution. No measurable amount of adsorption of the salt, asa whole, or of selective absorption of the base, so as t o leave thesolution acid, was observed, even when the solutions wereevaporated at the ordinary temperature in a current of air, orexposed to the action of a stream of carbon dioxide.The authorsgive an empirical formula connecting the amount of change with theconcentration of the ammonium salts in the solution when theamount of clay in equilibrium with the solution is in excess, butJ9 Abssty., 1907, ii, 717. 2o lbid., 1899, ii: 449.21 Trans., 1907, 91, 877268 ANNUAL REPORT8 ON THE PROGRESS OF CHEMISTRY.do not establish any theoretical justification for the formula arrivedat.The authors also considered the interaction of ammoniumsalts and calcium carbonate, but showed that the presence of thisconstituent affects but little the removal of ammonia from solutionby the clay and humus. They therefore regard the retention ofammoniacal fertilisers by the soil as due to clay and humus withoutthe preliminary reaction with calcium carbonate that is sometimesregasded as necessary.R. A. Robertson, Irvine, and Miss Dobson22 have begun a freshstudy of humic acid, which they have extracted from peat, and alsoprepared by the action of hydrochloric acid on sugar. The elemen-tary composition of the two products were compared, and, besidesdifferences in the percentage of carbon, the natural acid always con-tained nitrogen, and probably iron.It yielded fewer methoxylgroups than did the artificial acid, and, when compared as a sourceof carbon for the growth of Penicil'lium, the artificial acid wasbetter than the natural, but inferior t o glucose. S. Suzuki 23 has alsoexamined natural humic acid by hydrolysing i t with strong hydro-chloric acid ; from the products, he isolated alanine, leucine, aspar-tic acid, and small quantities of proline and other amino-acids.Several reports on the analysis, chemical and mechanical, of aseries of English soils have been published during the year, and, asthe analyses have been carried out on a uniform system, there issteadily being accumulated a mass of data for a general chemicalsurvey of the soils of our country.C.M. Luxmoore 24 described the composition, mechanical andchemical, of one hundred samples of soil and subsoil from Dorset-shire, the soils being derived from each of the tertiary andsecondary formations between the Bagshot Beds and the LowerLias ; F. W. Foreman 25 dealt with soils from Cambridgeshire, gene-rally derived from the same formations as those discussed byLuxmoore, and S. F. Armstrong26 attempted to correlate the com-position of a number of meadows and pastures in the easterncounties with the chemical and botanical coniposition of the herbage.Soil Physics.The physics of the soil is, perhaps, a t the present time the mostneglected branch of agricultural science, yet it ought to be veryattractive to any investigator, if it were only for the bearing ithas on the practical operations of cultivation and managementof the soil, which are of such prime interest to the working farmer.See also A.J. van Schermbeck, Abstr.,22 Abstr., 1907, i, 894.z3 Bulb. (7011. Agr. T6ky6, 1907, 7, 513.25 J. Ayric. Sci., 1907, 2, 161.1907, ii, 648. BJ Beport, Reading University College,2ti Ibid., 283AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 269During the past year few papers bearing on this subject haveappeared, nor has any new line of inquiry been opened up. VonSeelhorst and his colleagues at Gottingen 27 have continued theirstudies of the effects of variation in the water content and tempera-ture of the soil on the composition and yield of various crops, theexperiments in this case being made on oats and spring wheat.R.S. Vinson and E. J. Russell28 gave an interesting series oftemperature readings to illustrate the well-known fact that thebottoms of valleys are colder than the slopes on either side. Theresults agree with the usual explanation that the cooled air flowsdown the sides and accumulates in the bottom of the valley, butthey also indicate that the actual river bank is warmer than landa little further back from the water, the rise in temperature beingparticularly marked on any piece of land more or less surroundedby water.Another perennial problem, the flocculation or coagulation bymeans of salts of turbid liquids, such as suspensions of clay inwater, has again been dealt with by A. D. Hall and G.G . T.Morisoi~.~~ These authors have endeavoured to obtain quantitativemeasurements by using a constant amount of a graded kaolindiffused in a constant volume of water. The effect of varioussalts, &c., on jars filled with such a turbid medium were estimatedby matching them against a standard series in which the floccula-tion was brought about by regularly increasing amounts of calciumnitrate. The authors show that the amount of material flocculatedwas proportional to the amount of flocculating salt added up t oa certain point, above which any increase of salt produced nofurther effect; there was no adsorption of the salt, nor did floccula-tion involve any growth or permanent aggregation of the fineparticles of the suspended matter.Conductivity measurements,while flocculation is going on, indicated that no perceptible changeoccurred in the amount of salts in solution. The acids were the mosteffective flocculators, and aluminium salts were almost equally eff ec-t h e . Calcium and barium were less than half as effective, mag-nesium came a little below calcium, potassium had only about one-fifth the value of calcium, and sodium only about half that ofpotassium, equivalent for equivalent. The nature of the acidradicle had an influence on the flocculating power of the salt, theorder being hydrochloric, nitric, sulphuric, acetic (the chloroaceticacids had the same value as acetic acid itself); the same compara-tive order held for the salts as for the free acids. Oxalic andtartaric acids were feeble flocculators; citric acid, glycine, or"7 J.Landw., 1907, 55, 233. 28 J. Agric. Sci., 1907, 2, 221.Ibid., 2442'90 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.phenol were without action. Soluble hydroxides such as causticsoda, potash, or ammonia opposed flocculation ; calcium and bariumhydroxides gave, however, positive effects, but much below thoseshown by their other salts, the flocculating effect of lime in practicebeing due to the formation of calcium bicarbonate, which is a veryeffective salt. Many substances, for example, bauxite and hydratedferric oxide, do not form true suspensions in water, which propertythe authors regard as conditioned by the presence of double silicates,which hydrolyse and yield a little soluble alkali on contact withwater.On this theory, flocculation is brought about by the neu-tralisation or throwing back into combination of the free alkali,although any final clearing up of the subject must be preceded byan explanation of the Brownian motion, which characterisesparticles in true suspension in a turbid liquid.Chemistry of the Growing Plant.1. Nutrition.-Although nothing very striking is to be reportedin connexion with the nutrition of the plant, Fenton's synthesisof formaldehyde 30 from carbon dioxide by reduction of the aqueoussolution with magnesium should be noted as the first reduction ofcarbon dioxide that has been accomplished a t the ordinary tempera-ture. This may be regarded as a step forward, although thesynthesis is not of a type which can be imagined as taking placewithin a plant's cell; still, the evidence seems t o be increasingthat formaldehyde forms one of the steps in the natural processof photo-synthesis. G.Kimpflin 31 detected formaldehyde in theleaf of Ayave by injecting a solution of sodium hydrogen sulphitecontaining p-methylamino-m-cresol, which forms a red precipitatewith formaldehyde, but not with other aldehydic compounds.Although the function of the various mineral constituents ofthe plant is very far from settled as yet, a number of contributionsto the subject have been made during the year. H. S. Reed32 haseliminated some of the difficulties inherent in the problem by work-ing with a l p like Spirogyra in water cultures, from which thepotash, the phosphoric acid, or other constituent in question couldbe-omitted as desired.In this way, he observed that, in the absenceof potash, all starch formation was suspended, and the granulesoriginally present in the cells gradually disintegrated and disap-peared. The lack of phosphoric acid proved very injurious, espe-cially to the reproduction of the cells; there was no mitotic divisionof the nucleus, and there was an abnormal formation of cellulose.30 Tram,, 1907, 91, 687. Abstr,, 1907, ii, 289,82 Ann. of BOta7L?, 1907, 21, 501AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 27 IIn the absence of calcium salts, new cell walls were imperfectlyformed, and the production of cellulose ceased, whilst miignesiumappeared t o be essential t o the activity of the chloroplasts, sincein its absence no oil globules were to be found, and the chlorophyllassumed a yellow colour. The latter observation is interesting inconnexion with the important work by R.Willstatter 33 and his col-leagues on chlorophyll and its derivatives, which they have shownt o be compounds of magnesium, without any iron.D. Lienau and A. Stutzer,% experimenting with oats, found thatphosphoric acid promotes thickening of the cell walls, which,however, was diminished by potash and nitrogen. In consequence,phosphoric acid most promoted the stiffness of the straw. Theseresults, as regards potash, are hardly in accord with former obser-vations, or with the known function of potash to promote carbo-hydrate formation.The long-debated question of whether the roots of plants secretean acid, which aids in the nutrition of the plant by effecting thesolution of the mineral constituents of the soil, has been thesubject of further investigation.Kunze 35 reviews the evidenceagain, and concludes that only carbon dioxide is excreted. Hedoes not, however, regard this as capable of bringing enoughmaterial into solution, and shows that the acid excretion from themycelium of fungi in the soil is more effective.Schreiner36 brings evidence t o show that the roots of seedlingsboth excrete acids and possess oxidising powers, but no argumentas t o plant roots generally can be drawn from the behaviour ofthe roots of autotrophic seedlings. Stoklasa and Ernest 37 alsoregard carbon dioxide as the effective natural solvent of mineralsin the soil, and have been continuing their investigations on theamount that is excreted by plant roots and by micro-organismsin the soil.Under natural conditions, they obtain 15 milligramsof carbon dioxide in twenty-four hours from a kilogram of the soilthey worked with.Work continues t o be reported on that much-debated question,the stimulus t o plant production brought about by minute tracesof metallic salts and other substances whicb in higher concentrationsact as poisons. Despite the numerous investigations on the subject,for example, by Raulin, by Loew and his pupils in Japan,% byJ. A. Voelcker in this c0untry,3~ the prime fact of stimulus byminute traces of poison cannot be regarded as established.In-creased growth has, doubtless, been observed t o follow the applica-83 Abslr., 1907, i, 69, 71, 784.B7 Zeitsch. Zuckcrind. Bohm., 1907, 31, 291.3b Ibzd.34 Ibid., ii, 47.36 Abstr., 1907, ii, 715.Iti Ann. Report, 1906, 257,Jahrb. fur. Wiss. Bot., 1906, 357272 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.tion of such substances to the soil, but, as may be seen from theeffects of antiseptics, previously reported, the soil is excessivelycomplex and its equilibrium is easily disturbed. Hence it is byno means safe to cnnclude that any increased growth followingthe application of a manganese salt, for example, is due t o thestimulus of the manganese to the plant. Kayser and Marchand 40have studied the effect of small additions of manganese salts t oalcoholic fermentations.They find that the start of the fermenta-tion i3 sometimes checked by the presence of manganese, but thateventually higher proportions of alcohol, glycerol, and acids are pro-duced from a given weight of sugar. Yeasts that have been habituatedto comparatively strong solutions of manganese salts by growingin solutions of gradually increasing strength become particularlyactive, and will both induce a more rapid fermentation and pushi t further, especially if a small quantity of manganese salt ispresent in the fermenting liquid. Bertrand 41 applied manganesesulphate a t the rate of 50 kilos. per hectare to land on which wheatwas sown, and obtained an increase in the total crop of 22.5 percent., the corn being raised 17.4 per cent., and the straw 26 percent.Here, again, there is no means of deciding whether theapplication of any other soluble sulphate might not have beenequally effective by bringing into solution some of the dormant basesof the soil. G. Salomone $2 and S. Uchiyama 43 report very similarresults, in which even manganese dioxide exerted a beneficial influ-ence on crops in the open field. A. Amos4.‘ attacked the problemfrom a different point of view. Various preparations of copper (ofwhich the most widely used is Bordeaux mixture, prepared by pre-cipitating copper sulphate solution with lime 45) are sprayed on theleaves and act as fungicides, but they are also credited with bringingabout a longer life of the leaf, and an increase of crop, when no fun-goid disease attacks the plants.Flowers of sulphur are dusted on t oleaves for the same purpose. To ascertain if these substances actedas stimulants to the processes carried on by the leaf, Amos com-pared the rates of assimilation of two leaves upon the same plantbefore and after one of them had been treated with the fungicide,using Brown and Escombe’s apparatus for the measurement ofthe rate of assimilation. The only result of the treatment withthe fungicide was such a falling off in the rate of assimilationas might be expected from the inevitable blocking of the stomata,nor was any indication obtained that the activity of the leaf was40 Abtr., 1907, ii, 288, 383, 903.#l Abstr., 1907, ii, 982; also W.van Dam, ibid., 649.43 Bull. Cent. Exp, Sia. Japan, 1907, 1, 37.44 J. Agric. Sci,, 1907, 2, 257.J1 J. d’dgric. Pratzque, 1906, 42.4s Pickering, Tram., 1907, 91, 1988AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 273maintained to a greater age as a consequence of the treatment. Theexperiments were made with the leaves of the vine, and hop, andthe artichoke (Helianthus tuberosus), for which plants values ofthe rate of assimilation had not previously been obtained.2. Plant Conatitucnts and Changes of Composition durkqGrowth.-During the year, T. B. Wood has made an important steptowards the resolution of a problem, the cause of “ strength ” inwheat flour, which has long occupied the attention of agriculturalchemists in all countries.The question was the subject of a fulldebate a t one of the meetings of the Chemistry Section of the BritishAssociation, and Wood’s papers are published in the Journal ofAgricultural Science.46 Wood considers that strength, defined as thecapacity of making large, well-piled loaves, is the outcome of twofactors, one determining the size, and the other the shape of theloaf. The size is determined by the amount of carbon dioxideevolved in the dough, and this depends on the amount of sugarcontained in the flour, together with that produced by diastaticaction while the dough is rising. The shape of the loaf is deter-mined by the consistency of the gluten, which does not dependon its composition, but on the salt content and acidity of themedium with which it is in equilibrium. Wood found that thegliadin and glutenin, of which gluten is made up, possessed thesame composition (as far as might be judged from theproducts of hydrolysis), whether they were derived from strong orweak flours.By suspending pieces of washed gluten in a seriesof solutions in which both the acidity and the salt content variedby regular increments, Wood observed that for certain concentra-tions the gluten was tough and stable, while for others it disin-tegrated and lost all coherence. When the observations were allplotted with the salt concentrations as ordinates and acid concen-trations as abscissz, a closed curve could be drawn, all point3within which represented solutions in equilibrium with the non-coherent gluten.Gluten, however, in contact with solutions repre-sented by points outside the curve remained tough and elastic.Wood has discovered various relationships between the effect ofdifferent acids and salts known or likely to occur in flour, but theprecise application of the facts to the discrimination of strong fromweak flours remains to be worked out, a method for doing whichis indicated. Little is known as yet of the nature or amount ofthe acids and salts present in an aqueous extract of flour, but theseexperiments show that they must exert a marked effect on theconsisfency of the gluten, so that in their variations a clue may befound to the abnormal behaviour of many flours. Wood also shows4ti J. Agric.Soc., 1907, 2, 139, 267.REP. -VOL. IV. 274 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.that the consistency of other proteins, for example, the curd ofmilk, is similarly determined by the acidity and salt content ofthe solution with which it is in contact, and suggests that in thisfact we have a general clue to the control of all such technicalprocesses depending upon the physical properties of colloids.Thatcher and Watkina 47 have studied the distribution of nitrogenin the different grains from the same ear of wheat, and again indifferent ears of the same variety. Their work goes to show thatt’he variations thus found among the different ears of the samevariety and between the grains of the same ear are due to nutri-tion, and are not hereditary. This result a’dds another to thearguments against the possibility of improving plants like wheatby (‘ selection ” alone.Several facts of considerable chemical interest in connexion withthe membranes forming the coats of seeds have been publishedduring the year.In the first place, A. J. Brown 48 has shown thatthe barley grain possesses a true semipermeable membrane, throughwhich water will pass freely, but not any of the salts which maybe dissolved in the water. I f , for example, unbroken barley grainis immersed in normal (4.9 per cent.) sulphuric acid, water onlypassed through the membrane into the endosperm, until the sul-phuric acid solution outside became concentrated up t o 7.6 percent. The grain also absorbed water from 18 per cent. sulphuricacid, but failed to do so from ilr solution containing 36 per cent.ofacid. The effective membrane appeared to be located in €he spermo-derm, since this layer resisted the action of 36 per cent. sulphuricacid, by which the outer layer of cells forming the pericarp wasdisintegrated. Iodine was the only dissolved substance that wasfound capable of passing through the membrane, and it seemssignificant that the substance so doing should also be one com-bining with the starch of the endosperm.C. Bergtheil and D. L. Day49 showed that the irregular and slowgermination of the seeds of Java Indigo (Indigofera arrecta) wasdue t o the preponderance of ‘(hard” seeds, formed only when theseed crop was allowed to become thoroughly ripe.These hard seedsare practically impermeable to water, owing to a thin outer cover-ing, neither true cellulose nor true cuticle, which can be removedby scratching or by steeping the seed for half an hour in concen-trated sulphuric acid, followed by immersion in water.Similar “ hard ” seeds in clovers and other European leguminousplants have been studied by Hilbner and Kin~el,~O who recommend47 Abstr., 1907, ii, 983.so Zeitsch. fiir LarLdw. ZL. Forut. FVirts., 1906, 36.A w . of Botmy, 1907, 21, 79.49 Ibid., 57AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 275treatment of the seed with hot water or sulphuric acid in orderto promote germination.Amongst other papers dealing with plant constituents, one shouldbe noticed by E.Schulze,51 in which he maintains that the darken-ing of beet and other plant juices is not due to the enzymic oxida-tion of tyrosine, as is commonly supposed. The tyrosine he couldobtain from the juice of beet, potato, and dahlia tubers was toosmall in amount to account for the darkening; moreover, afterdarkening, the tyrosine was still there, and no trace of homogen-tisic acid could be detected.I n the chemistry of enzyme actions, we owe to F. Ehrlich 52 theinteresting observation that fuse1 oil in alcoholic fermentation isderived from leucine. The leucine is split up by the enzymes, andthe nitrogen-containing groups are used for the formation of pro-teins in the yeast cells. Ordinary leucine yields inactive amylalcohol ; isoleucine gives Z-amyl alcohol.Munures and Munuring.As regards fertilisers, the year has nothing new to show; bothfield and pot experiments continue to be made with the two newproducts containing nitrogen derived from the atmosphere, crudecalcium nitrate and calcium cyanamide,53 and agree with previoustrials to show that the nitrogen of both substances is in a highlyavailable condition.But neither product is yet on the marketon any large scale, although the small factory a t Notodden iscontinually turning out calcium nitrate, and the Italian CyanamideCo. at Piano d’Orta are rapidly increasing their output. It isunderstood that very large works are being erected for bothprocesses, so that next season may see these fertilisers on theordinary market.Meantime, the two substances with which the new fertilisers willmainly enter into competition, ammonium sulphate and sodiumnitrate, continue to receive considerable attention ; there has beenquite a revival of investigations into the relative value and actionson different soils of these two old-standing manures,54 although itcannot be said that any new point of view has been disclosed.Turning from the most recent to the oldest of fertilisers, farm-yard manure, Schneidewind,bS at Lauchstadt, has been continuingthe very interesting series of researches begun by Maercker on theAbstr., 1907, ii, 293.Ibitl., 383.53 Ibid., 48, 295, 573, 646, 807.5J H. Siicbting, ibid., 646 ; Schneidewind, Lniwlru. Jahr., 1907, 36, 598 ;O9 Zaitdw. Jahr., 1906, 36, 569.Kretschmer, &c., Abstr., 1907, ii, 809.T 276 ANNUAL REPORTS ON THE PlLOGRESS OF CHEMIBTRY.losses of nitrogen that are experienced in making dung and thebest methods of conservation that can be adopted in practice.These investigations have the great advantage of being madeon a large scale and under working conditions, and are not opento the objections which attach to most of the laboratory experimentsthat have been reported on materials for conserving dung. Schneide-wind pronounces against gypsum and other materials of like nature ;not only are uneconomical quantities necessary t o be effective insaving nitrogen, but the calcium sulphate becomes reduced tosulphide, which afterwards acts injuriously in the soil. Instead,he confirmed his former observation that the greatest saving ofnitrogen is effected if the base of each new dung-heap is madeof a layer from an old fernienting heap Schneidewind has hardlyarrived a t an explanation, but he thinks the difference may bebrought about by the carbon dioxide evolved from the initial layer ;of the experimental fact he has no longer any doubt.The losses of nitrogen in making farmyard manure have alsobeen studied by T.B. Wood 66 in the course of a feeding experiment,in which four heifers received known weights of food, which wasanalysed from time to time. The dung was not disturbed, but wasanalysed by cutting out sections a t the end of the feeding period,and again six months later. About 15 per cent. of the nitrogenin the food and litter was lost in making the dung, and on storagethe loss increased to 28 per cent.for poor dung made from rootsand hay only, and to 40 per cent. for the richer dung obtained byfeeding also with cotton cake. Since the digestible nitrogen in suchrich foods is excreted as urea, which readily ferments and under-goes loss, even under good management, it is not always possibleto recover in the manure the half of the nitrogen contained inpurchased foods, which is the basis now usually adopted for com-pensation to the outgoing tenant for the fertility he leaves behindon the farm through the feeding-stuffs he has bought and con-sumed during the last year of his tenancy.Chemistry of Animal Nutrition.A paper which is likely to have a considerable bearing on thetheory of animal nutrition, since it throws light on the fact wellknown to practical graziers that the proteins of different foods havenot the same values for putting on flesh, has been published byMiss Willcock and F.G. Hopkins.57 They showed that when zeinis the only nitrogenous food given to young mice, they soon die,but when tryptophan, which is absent from zein, is added, thesurvival of the animals is greatly prolonged, indicating that the56 J. Agric. Sci., 1907, 2, 207. 57 Abstr., 1907, ii, 109AGRICULTURAL CHEMISTRY AND VEGETABLE PHY SIOT,OGY. 27’7tryptophan group is necessary in building up the proteins specificto mice, and that i t cannot be replaced by similar amino-acidslike tyrosine.The view, now generally accepted, that in digestion the proteinsare broken down very thoroughly into simple amino-acids andkindred bodies, which are put through a building-up process inthe intestinal wall68 before they reach the blood, has continuedto receive much discussion.It is well illustrated in an investigationof Abderhalden and his colleagues,59 who found that feeding adog on gliadin (a protein very rich in glutamic acid) did notincrease to any marked degree the amount of glutamic acid in theblood proteins. Bound up with this subject is the question of theutilisation by animals of the non-protein nitrogenous materials infeeding-stuffs. 0. Kellner 6o maintained that they can, to a certainextent, replace proteins in the diet, because they become built upinto proteins by bacteria in the intestine of herbivorous animals;M. Muller 61 finds that soluble non-proteins from hay can be utilisedin the formation of flesh of a dog, whilst I(. Friedlander 62 found thatthe non-proteins of molasses fed in conjunction with food deficientin nitrogen were unable to prevent loss of nitrogen in the animal,although most of the nitrogenous compounds in the molasses couldbe converted by bacteria into proteins.The parallel question of how far animal fat in the body or inthe milk is reconstructed from the fat in the food is discussed ina paper by von Knierim and Bus~hrnann.~3 Feeding milch cowswith various oil-cakes, they found that both the milk yield and thecomposition of the butter fat, as measured by its physical properties,were affected by the feeding in a way which could only be explainedby assuming that some of the fat of the food had passed into themilk unchanged. How far the fat had been broken down in digea-tion and then built up again was not discovered.A nutytical.The determination of phosphoric acid continues to attract a gooddeal of attention; in most countries, the accepted method is toprecipitate as phosphomolybdate, which is dissolved in ammonia,the phosphoric acid being reprecipitated with magnesia mixture.Since it is a lengthy and comparatively expensive process, manyalternatives have been suggested, and two long and critical papershave appeared in 1907 by Mach and Wagner, Kunze, and Simmer-IIs Abstr., 1907, ii, 893.6o Ibid., 491, 794.59 ]hid., 487.%d., 645.63 Lrcndw. Jahr., 1907, 36, 185. Ibid., 895.84 Abstr,, 1907, ii, 395278 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.macher,65 showing that equally accurate results can be obtainedby direct precipitation with magnesia mixture in the presence ofcitric acid, if the silica be first removed. A critical paper on theestimation of potash as perchlorate, as applied to agriculturalanalyses, has been published by Schenke and Kriiger,66 who showthat sulphuric, phosphoric, and hydrochloric acids must first beremoved.A. D. HALL.65 Abstr., 1907, ii, 577. 68 B i d . , 910