714 
The Nitrifying Ferments of the SoiL 
set into a solid jelly by the addition of a little of the liquid to 
be nitrified, he has achieved complete success. By stabbing or 
spotting a sterilised slab of this with a wire dipped in a nitrify- 
ing culture, it is found that the foreign microbes will not grow, 
whilst the nitrifying, organisms will, and soon nitrification can 
be detected all through the jelly (the writer has succeeded in 
repeating this experiment). By this improved process the 
organisms can be much more rapidly obtained from soil than by 
any other, and also in greater purity, for, as Winogradsky has 
shown, it is not a safe assumption that a liquid which will give 
no colonies on gelatine after a few days' incubation is absoluielij 
free from microbes other than the nitrifying ones. Gro-vvn in a 
pure solution inoculated with a colony from the silica jelly, these 
organisms are seen to consist of an oval or nearly round coccm 
or bacillo-coccus, of varyiug size, reaching nearly xjowo ^^^^ 
diameter in the largest. 
The antagonism of the nitrifying ferments to organic matter 
has received from Winogradsky a most striking explanation. 
He has shown that they obtain their supply of carbon in a 
manner unique amongst known living organisms, namely, from 
the carbonic acid of the carbonate of lime or carbonate of 
magnesia contained in the soil or added to the liquids in which 
they are cultivated. Indeed, these mineral particles ai"e, in an 
old nitrifying solution, seen by microscopic inspection to be 
literally eaten or dissolved away by attacking masses of the 
organism, which thus present a perfectly characteristic appear- 
ance. 
The importance of this discovery is very great ; it reveals an 
entirely new property of living things, that namely of building 
up from the carbon of minsral carbonates and the nitrogen of 
ammonia, the complicated albuminoid and other organic constitu- 
ents of living cells. It appears that about thirty-five parts of 
nitrogen in the form of ammonia have to be oxidised to a nitrite 
for one part of carbon taken in as food by the ferment, and it is 
the heat evolved by this large oxidation that furnishes the force 
necessary to effect the decomposition of the carbonate." Wino- 
gradsky speculates on the rule these organisms may play in 
nature in preventing the accumulation of the supply of carbonic 
acid in the form of mineral carbonates (as is well known, chalk 
and other carbonates of lime are formed in the first place by the 
agency of life). Another fact of a remarkable nature soon 
appeared. 
The purified organisms of Frankland, Winogradsky, and 
Warington, whether identical or not, agreed in this, that, 
although they would entirely nitrify ammonia, they would con- 
