NEW BOOKS Bacteria in Relation to Country Life. / ? j , JIICIJ~ i,'. f 2 i f i v i ( i u , 1.3 X i y C H ; iimi'ii 486. .\-G ).orkc 7'hc .\fiicm!llii~l C ' O ~ ~ , I ) I , I 1908. , Iit.ii-i: $ r , . j o iici.-The subject is divided i n t o eight liarts: structure and grii\\ tli of lxicteria; h c t e r i a in air and w.iter: 1i:icteri:i nn.1 sewage; lncteria in relation t , i soil iertility ; tmcteria in Iiarnyard nianure; Imcteria in milk a n d related ~ ~ r ~ i c l u clixctcria ts; in relation t o preservation I I food ~ ; Iiacterin a n d fermentation. Tlie Iioiik is :in interesting cine and ciiti lie cqieneti almost anyn.here J v i t l i profit. Tlie follo\ving quotations will illustrate this. Intiiiiately cc~nnected\vitli tlie life ~ir(iccssesc i i lxicteria is the aliility of suiiie sliccies t o produce pigments. ?'lie ccil(iring riintteri Iirocluceti I Jdifferent ~ , red, 1)lue. liink, viiiiet, green, Iirowii, species include giiltlen y e l l ~ ~ wcirange, [ind Iilack sul~stances. 13lue or red milk, and even Iiluisli o r yclloiv litis i n \r.ciuntls ~ i i a ylie produced tiy Iiacterin." "Tlie aliility to ~)r(icluce~ilios~~liorescence is :I ]ir(il~ert>-lield Iiy certain species of Ixicteria in cotnriion l v i t l i some niemliers ( i f the anitiial kingtliini. These bacteria, designated as ~ / ! f J f i ~ ~ i ~ ~ i - f ~are, , ~ j l zs ,o far :IS is kniitvn all in1ial)it:ints of the s e a ?'he phosphorescence of sea-\\ atcr. a ~~lieni~riieiicin riiucli c o n niented til)on, is d u e largely, tliougii not entirely, to Iincterin. I t is these organisriis. a l s ~ tliat ~ , liroduce plios~ilioescence in decaying fish a n d m e a t . " "flort,:tiiz o i i i i ,.~.spi',.~~fiiiri.-'rlien u n i l x r o f liacteri:~ in the air civer the ocean, over high niountairis. in 1)olar regions, or in countries scaiit rainfall, is relatively very sniail. Conditions there prevent Iicitli tlie addition of large nurii1m-s t o the attiicis~iliere, :is \\-ell as t h e survival of (lie 11:icteri~i:ilreatly there. O n the contrary. the air o f city streets a n d of liuriian tl\vcliings is ~i:irticularly rich in rnicroiirganisins o\ving t i i ciinditiciiis favoring liotli tlie addition of large riunibers t i l the :itriios~~Iiere anti their survival there. "These facts are of very cc)nsideral~leniiiiiient from the stantll~iiiit O i hygiene :Inti sanitntilin. l\.e k i i t i \ ~ t h a t , not\vitlistanding t h e large nunilier of bncteria i n the atnicispliere. the air expired from the huiiinn lungs is i)r;ictic:illy gerIii-free. This means t h a t the niicr(iOrganisn~~ Lire retained i n the nose, r r i i i u t h , and throat, and t h a t ninny of them :ire carried with the dust ~iarticlesinto the lungs. Enorrnous numbers of liacteria are t h u s retained. and i t is iilivious t h a t , everything being equal. the danger friitii iniecticm is greatest \r.hen the nurnlier c i f Iiacteria in the air is greatest. I'cxrsrins leading a n incli~irexistence, and tli(ise living in large cities, inhale morc 1)acteria and are niiire exposed to infection t h a n peii1)le living i n the country. " I t does not follow, a t tlie sanie time, tliat the danger i i f ci1ntr:icting a disease, say tul~erculosis,is greater in tiie suiiinier t h a n i t is i n tlie \r.inter, siiiilily liecnuse there are more germs aliroxi. ;\iter d 1 , most d tlie Iiacteria in tlie : :r :ire h:irniless, a n d i t is very likely t h a t tlie a c t u a l nuinlier ( ~the i germs of tulierculosis and pneumonia i n the \\-inter air is ,Treater t h a n t h a t in the wnirncr air." " S C i j - ~ i o . 2 ' j i c i I f i o i ii i j tiyi.,.s.-'rhe activities o f tiie \\:iter :ind se\\nge Iiacteria rapidly exhaust the store o f readily deco~nliosaiilecirg:inic inaterial. T h e less readily availalile residues do not furnish the large quantities of food required
+
pp.
"
161 tnins a varial)lc niiln1)cr
cii
li,ictcri~i,tlclietidiiig oti tlie Iiurity oi tlie \\:iter em-
liliiyed
Iiactericiliigical esniiiination.: IJT thick cakcs ( i f natural ice have shown th:tt, ;is tlie free/ing I)roceetls friiiti the t o p do\vti\\ artl, the nuiiilier ( i f liacterin I d Iiacteria has heen inclutletl in the ice tiiiilinislie.;. 'lhc greatest ~)rolicirtic~~i found t o occur i n t h e sno\v-ice. altlitruyll on tlie nliole, there seems t o IIC no uniforin tlistriliution ( i f the lxicteria in a n y one layer. Their nunilier rimy vary iroin less t h a n cine huntlretl to several tlliiu?:intl ~ i e rcuhic centimeter. .is the ice tiielts, the nuiiilier ( i f lxicteria in the ice-\v:iter liegins t o increase, [ittaining :it times, x-ery consitieralile 1)roportions. ()tie instance is reiicirtetl in ~vliich:I piece of ice lvns iiielted :inti irntiietli:itcly cx:iininetl. Tlie tiutnljer of organisms per culiic centimeter. \\;is I O X , I\ 1ierc:is. eleven d:iys later the ice-water W:IS iciund t o contain ~ x ) , o o ( 1):icteria. i " T h e partial destruction of the bacterin Ijy ircczing, nnd their sulisequent multililicatiiin in tlie ice-xater. m a y have t i direct lienring o n the typhoid cluestion, since i t has lieen oljservetl t h a t not all o f the Imcteria are ali'ected to t h e same extent Iiy freezing. I t is cluitc 1iossiI)le that tlie disease germs niay survive in tiiucli greater 1irol)ortion than tlie 1i:irnilcss liacteria, and i x i p sulxeciuently niuIti1)ly :is tlie ice melts. Tyl)hoitl germs (11) n o t apliear t o suffer from tlie cornlietition o f other liicteria :it Iciiver temperatures so niucli :is they suffer froin i t a t higher temperatures. S:i\-:ige states t h a t ":it the tetrilierature of t h e ice-chest, the tyl)lioitl germ m a y groiv i n tlie liy-lmidiicts c i i other germs, which, a t higher ternl)eriiturcs, a r e quickly f a t a l t o it." " I n Selitemlier. I ~ , < I :i, Ixitent for 'Tlie ;\utorn:itic ant1 odorless S w v e n g e r ' \vas granted t o 1Ii1uras i n France. The ;\tnerican Iiatent granted to AIouras is d a t e d Sovemlier ?,-ears,although usually i t is succeeded a t the end o f t h a t time by other crops. like mangolds or c a b tiages. o n some of the irrigated inendon-s the rye grass has been replaced b y a mixture ( i f native grasses \vliich likelvise produce heavy yields of d r y matter. ;\lfalfa has also lieen grolvn successfully o n sewage-irrigated lands near Paris a n d i n our \vestern states. Like t!ie Italian rye grass, it transpires enormous quantities oi water. 0 1 1 t h e ivhole, however, leguminous crops are not a d a p t e d for sc\vnge-fnrrns." ' ' T h e r e exists unciuestionalily a n irnl)iirtant relation ljetween the crop on the soil a n d the nuniliers and kinds oi Iiacteria u i t h i n i t . For one thing, t h e leafy crops t h a t sliatle the soil create ccinditions as t o moisture, temperature a n d light t h a t a r e difierent froin thiisc created l)y cereal crops. T h e differences do not, hy a n y riieans, s t o l i there. T h e crops take ~)lant-foocl and moisture from tlie soil and give Iiack t o i t some t r f their suljstance. something that passes o u t of tlie roots :ind into t h e soil. o u r knoivledge oi the amount and nature of t h e su1ist:inces thus gi\-en u p t i , the soil liy tlie ~ i l a n t sis menger. I t is not knotvn as yet to \ \ h a t e i t c n t these secretions influence the numliers and kinds There is reasiln t o tielieve, however; t h a t a ciecidcd I J ~ Iiacteria in the soil. influence is thus exerted tiy the grciiving crops. These affect the grou tli oi soil 1)ncteria in still another ~ v ~ i y . " I t is a weIl-kni)\vn fact that different crops do not take o u t of t h e store of avni1al)le ccinstituents in tlie soil tlie sariie a m o u n t s iind p r o p r t i o n s of plantfood. For this re:isi)n, t h r y affect the ciiiiil)usitii)n of t h e soil t o a n unequal extent and uneciu;illy change the nuriil)ers anti character of the soil Iiacterin. The effects ( i f different systems of croliliing are clearly distinguislia!)le tjoth i n the size anti quality o f the harvests and in the endurance of soil fertility. The I)ernicious effects of the continuous growing of cereals were noted generations ago, a n d led gradually t o the introduction of rotation systems. I t seenis t h a t the evil effects of continuous grain-groxing are due in p a r t to t h e one-sided and wasteful changes in the soil-humus caused iiy bacteria. On t h e other h a n d , a succession of different criips, including nieniliers of tlle legume f:imily, creates c~intiitiiins i:iv(iring an ecciniimical transformntion i i f the si)il-humus. I t will
ATCW
Books
t h u s be seen t h a t there is a direct relacion Iietwcen the crops on tlie soil and tlie liacteria in tlie soil. " T h e numlier of soil bacteria varies likewise with the methods of tillage. All of the mechanical operations. such as plowing, harrowing, disking, hoeing, a n d rolling, which affect tlie evaporation from tlie soil, the penetration of air, or tlie supply of moisture from the sulisoil b y capillary action, affect the rate of increase of the soil bacteria. The nunihers of liacteria in the soil are readily affected by the application of manures and fertilizers as well as by the turning under of green-manures. \\.hen a n y of these manurial substances are introduced into the soil, there are changes prciduced in its content of solulile salts, a n d , likewise, modifications in its nioisture and aeration conditions. An additional factor is introduced in the case of liarnyard manure, since the latter is a material rich in bacteria. - i n application of several tons of nianure per acre introduces into the soil many millions of bacteria, and not only adds thus to tlie nuniliers already present there, b u t also influences the rate of sulisequent increase." "Quality of iiunius as aij'ecfiiig number of bacteria.-The influence of tlie quality of humus on the soil liacteria is also iinportant. The so-called mild iiunzus, or mull, of arable soils, or of woodland, is different in its composition from the ax iiuwzus of heaths, meadows, and swamps. I t influences in a n entirely different way the numliers and character of tlie Iiacteria. The differences observed are due largely to the origin and mode of formation of tlie two c1:isses of humus sulistances. The mild humus is formed under conditions admitting tlie free access of air and through the activities largely of a@robic organisms. I t is either neutral or alkaline in reaction. The raw humus is formed through the process of putrefaction rather t h a n that of decay. I t is acid in reaction, and is not a suitable medium for the development of most hacteria. I t has been shown t h a t peat lands contain a relatively slight numher of bacteria before they are reclaimed and placed under cultivation. \Then drained and limed. tlie number of bacteria soon increases from a fe\\ thousands to many millions per gram of soil." " imp or ti^ pice ( ~ ,i~t,.ii?Cc't&ii1.~Tlie j vast practical significance of nitrification processes is apparent from tlie fact t h a t most of the nitrogen used h y crops is taken u p in the nitrate form. \Thile there is much evidence a t hand to s h o ~ v t h a t many plants arc caliable of utili7ing ammonia as readily as nitrate nitrogen, yet, because of the very rapid conversion of animonia into nitrate, the latter is almost tlie exclusive source of nitrogen. The rapidity ivitli which aninionin salts are changed in the soil to nitrates is attested b y the experience a t Rotlianisted in England. I t \vas tlie practice there to a p p l y the nitrogen on certain plots in tlie form of ammonium sulphate in the fall. I t \vas soon noticed, 11o~vever, t h a t , notwithstanding the lateness of tlie season, the ammonia was rapidly converted into nitrate as shown Iiy the increased contents of the latter in the drainage-water from those plots. I n fact, the application of the ammonia salts was practically equivalent to tlie application of nitrate, and, in order to guard against the loss of nitrogen, the fall applications of amnionia salts were discontinued." " I t has already lieen stated t h a t tlie application of ammonia salts in the fall is wasteful liecause of its ready conversion into nitrate, even in the late fall.
I n fact, nitrification sceiiis to go on until tlie s r i l is xlniiist frozen. TYhen a crop is irccul)yiiig the l a n d , t h e nitrate iis i t is fnrnied is t:iken uI) 1)y the 111:intsanti b u t little allo\\etl tii esc:ilie into the tlrxins. IVlien the 1:ind is kel)t liare, the nitrates fornied a r e \vaslietl into the tlcelier layers oi tlie soil a n d may lie carried d i Iiy the drainage. It is for this re:ison 1):irtly tliat tlie ciintinuous growing o f ivlieat is :I wnsteUul procedure. l‘lie land is kept 1)nre :it n time c i i t h e year when t h e nitrificatiiin processes in tlie soil a r e niirst :ictive, resulting in t h e loss o f w r y consideralile c1u:intities o f nitrates. Investigaticins have s h o n n t h a t i n t h e ciintinuous grciivitig of lvlieat there m a y I)e four to six I)ciuncls oi nitrogen lost from the soil to every pcriind removed in the crol).” “ . S u j / - ~ i i ~ c ~ ~ ~i ~ i i i ~/hi. ~ ~ ’Ti ./i / i t c ~ Z Stcitr~c.--?’Iie history of soil-inoculation efiorts in the r n i t e d Stcites is, in ni:iny resliects, unique. As in Germany, tlie first nttenilits a t inoculntiirn involved t h e application ( i f legume-earth :is inoculating inateri:il. Crnps like clovers. cow-peas, fieltl-pens, Ileans, and even vetches did not ap~i:irently require a n y inocu1;iticiii. .is :I rule, they groir on ne\v soils rather \-igcirously a n d ~iroditcedthe cliaracteristic nodules, t h u s indicating that tlie I)roIier lincteria a r e Iircsent in most soils. I t \\-:is otherwise v-it11 a t least two leguminous crops. sci>-lieons and n l l n l f a Siiylxans. originally introduced into t h e United S t a t e s irotn JaIiaii, did not tin very well. T h e y frequently failed to develoli tliat healthy, &irk green color c1iar:icteristic of vigorous leguminous 1)lants. C:ireiul esaniinaticin slion.ed tlieir routs to lie devoid of tuliercles. Soy1)eaii earth, straw a n d clinfi )\ere olitainetl from Japan and placed i n tlie grniinil together \vitli tlie seed. ?‘lie ~ i l a n t st h u s inocu1:ited developed nornially : m l ~iriiducetian aljuntlnnce of tu1)ercles. his experience dentonstrateti tlie need of soil-inoculation fur soylieans. X a n y cases Lire rel)ortetl in eslierinient stntion literature i n which these inoculations gave positive results. I:or instance, in the esperiinents i i f the S e w Jersey Station. o n light sandy soils a t I-Iainmontcin, ivlien cowljeans a n d soybeans were Iilantetl in the same ground, the iornier fire\\’ lusuriantly :ind gathered nitrogen from t h e air Iiy means of tlieir riitmcrous nodules. ivliile tlie soybeans rem:iined stnnll Lint1 yello\v ant1 priiducetl no tuliercles. I t \vas not until t h e introt1uctii)n ( i f s i m e stiil fri)tii :I iield \vlicre tliese plants 1i:itl l)een grinvn sticcessfully for s e v e r d years t h a t tlie soylicnns tle\-elo~retland grew as luxuriantly as dit1 t h e CU\I I’eas. iinilar oliservatiotis iverc nincic time and again in tlie case of nlfalia. Soils to it-liich this crol) \\-:is new usually recluiretl inoculation, even though they Ii:iti successfully I)rodiicetl red or criiiisiin clover. I t appeared, as i n tlie case cif siiylieans, t h a t the 1i:icteria cal):ilile o f producing nodules on alfalfa v e r e absent, as a rule, from sciils in \vhich this crop had not Iieen raised hefore. This observation has led to the r:itlier c ~ i i i n i o t ipractic of scattering old alfalfn soil o n new fields wliere this Iilant \Y:LS to lie estnlilislied. 11 \vas found subsecluetitly t h a t tlie h c t e r i a causing niidule-lorinntion on :ili:llfa ivere seemingly identical w i t l i those producing tiiliercles o n sweet clover, Inoculation \vas thereicire su~ieriluouson sciils to \I hich s\veet cl(rver \vaq native. a n d . moreover, sit-eet clover soil could lie used a s incicu1:iting tn:iterial iiir nen- alfnlia fields.” ‘ ‘ l i t z c / i rjol cirtii i/l’c,i i i i i d n i o i i c j ’ iiic.ccs.---’I‘he e s t e n t of t h e monetary losses inrnlveti in the inipr~iperccititrcrl of t h e 1i:icterial activities i n manure tnay I)e :ii)~ireci:itctl ircrrti tlie fiilliin-ing ciinsider:itions. Taking t h e amount i i f manure
Arew Bonks and litter for each cow a t 1.5 t o n s annu:illy antl for each horse a n d mule a t .j tons :innually, we find, in roilntl nuiiiliers, 130 Ixiunds :inti ,io p(iunds of nitrogen respectively t o lie credited to exch :inini:il. \\.it11 a value of only S cents per p u u n d . this nitrogen n.oultl l)e \r.orth S I L ) a, n~d 54 respectively. \i7ith, say, 6o,ooo,ooo of cattle anti ~o,ooo.ooohvrses a n t l mules in the Vnited Stntes, t h e v:ilue of the manurial nitrogen \vould Ije greater t h a n 5;00,ooo,ooo. .lssuming t h a t tlie difference Iiet\ceen economical and \vnsteful transforrnation of this nitrogen in t h e innnure Iiile l)y Iiacteria \voultl represent 2 0 Iiercent, tlie nionet a r y loss would a m o u n t t o S I ~ O , O ~ O , O O O . " ' . -\ tiiicroscopical esaniination b y Grotenfelt i i f the dirt particles in unstr:tined. freshly drawn itiilk revealed the Iiresence of the following sullstances : 1. \Innure--pnrticles
(nun~er(ius).
2 . Fodder -particles
( h n d n o t ~ ) n i w dtlirrmgh tlie alilncntary canal of tllc aninials) .
.i. \Ii,lds nnd ot her i u n y i . 4. C o v hnir (nuiiier,iui)
5 . Particles of the skin 6 , Hiinmil hai r.
7 . P a r t s r i f insects. 8 . nmvn
~IIIIII
birds.
9 , Small w , i , d e n pieceq. shavii~gs.2nd p i e c e s o f iir leaves. 10. \V
