G82 



iiEi'our — 1884. 



others which niin;lit ho possihly hd utilised. It is even (Mjiu'eivablo that animal lifo 

 could b«) suppoited l)y iiUotropic or isoiuerio fban).'e8, Huch iis the traiisl'Driiuitiim 

 f)f ainorphoiis into wiixy pluwphorons, (ir of amorplioiis into cryHtalline untimuiiy. 



Tlio author then desciiiied the chemicul chan;.'i'.s jji'odueed by a hir^'e niiiulur df 

 niicri)-or;.'anisui.s, and coneliided a^ tnilow.s : - 



Tiiere i.^ no breaii in the continuity ol' ciieniical functions between n\icri)- 

 orfranisnis, and the iiif^her forms of animal life. Hoth aliKe owe their vitality to 

 the lilieralion nf the t^ner^'y .stored in (heir fooil, anil both j.'o throiii^h a cycle (jf 

 existence and then lose tiieii' vitality. It is true that there are ap|)areutly ciitiiiu 

 .shai'p tlistinc tions between them. Tlius tht^ ennrniiius fecundity ol micro-orjriinism.s 

 am] their tremendous a])petilos (on the assumption thai all tin^ cliauj,'(.'d nialttr 

 pisses lhroni.di their bodies) seem to si'parate them from tlio hij^her orders of 

 animals. Ihit this distinction is only comjwrative. 



'I'hns in rej^'ard to fecundity, tiie power of nniltiplication pradnally increases as 

 Iheiinimal descends in the scale of or^'anisation. There are, of course, exceijtioii^^iliut 

 this is the rule. The sheep pi'oduces only one or two hunbs anniuiily. Tlie iieiriiij: 

 in the same time multiidies itself many thousandfold, whilst the aphis ]>riMhin's 

 youi.^' at such a rate, that a sin<,de specimen would, if all its proj,'eny livud, 

 produce in three months a wei^hl of aphides greater than that id' the whole con- 

 temporary lunmiu race. And, as to ap])etile, voraitity is c;i(iilesl in tlie lowi'sl 

 animals. A sheep or co'v consumes about oiie-sixtii of its own weight in tweat\- 

 fonr hours; an earthworm, a caterpillar, or a silkwiu'm, many times its own wei|.'lit. 

 The yeast oriranism nuist therefore, taUin;^ into accmnit its iiosition in natiu'c, Ije 

 considered decidedly abstemious, inasuuu;li as it oidy consumes two-thirds of its 

 own wei;,dit of sujrar in twenty-foiu- hours. Moreover, it must be borni! in ininil 

 that the slieej) converts nuich of its food into carbonic aniiydride, water, ami 

 hippuric acid, ihn.-; utilising nearly the whole id' the potential energy, whilst the 

 muro-organism, as a ride, utilises oidy a small pm-tion. Further, those micro- 

 organisius which have been chemically stmlieil ])rodnce, like the higher aniniul,'-, 

 perfectly delinite chemical changes. There is in tiiis respect, therefore, no essentinl 

 ditference between a mass (d' yeast, a jiopuloua town, a herd of cattle, and a colony 

 of snakes; each ])roduces its own peculiar chemical changes in the food it consumes, 

 and thereby obtains the energy uect'ssary to its vitality. 



The position of micro-organisms in nature is only just beginning to be appre- 

 ciated. Tlieir study l)oth from chemical and biological points of view is, however, 

 of the highest importance to the welfare of uumkind, and I \onture to predict tinit 

 whilst there is no danirer of their being spoiled by petting, or by their wcill'are 

 being nuide the special care of sentimentalists, these lowly organisms will ro.'L'iv& 

 much more attention in the fidure than they have done in the past. Their study 

 leads the iiKjuirer right into those functions of life which are still shrouded in 

 obscurity. 



.1 



2. 0)1 Nitrification. By R. Waiunoton.^ 



The Theory of NitnJicatim.—TiW the commencement of 1877 it was generally 

 supposed that the fornuitiou of intrates from ammonia or nitrogenous organic 

 matter in soils and waters was the result of simple oxidation by the atmospliere. 

 In the case of soil it was imagined that iLe action of the atmosphere was intensitied 

 by the condensation of oxygen in the pores of the soil ; in the case of waters no 

 such assumption was possible. This theory was most unsatisfactory, as neither 

 solutions of pure ammonia, or of any of its salts, could be nitrified in the laboratcrj- 

 by simple exposuinj to air. The assumed condensation of oxygen in the pores ot 

 the soil also proved to be a fiction as soon as it was put by Schloesiug to the test oi 

 experiment. 



l^^rly in 1877, two Fi'ench chemists, Messrs. Schloesing and Miintz, published 

 preliminary experiments showing that nitrification in sewage and in soils is the 



... ' The original paper will be found in full in Xature, xxx. p. G44. 



