1 1 8 Green. — On Vegetable Ferments. 
from the urine, &c., is removed by filtration, the clear slightly 
alkaline filtrate can decompose the urea just as the dried 
powder can. By repeated solution and precipitation the 
enzyme can be separated in a fairly pure condition, when it 
appears as a white powder, soluble to a clear solution in 
distilled water, and giving a very faint xanthoproteic reaction. 
Its activity is destroyed by heating to 80-85° C. 
If the original urine be filtered before the first precipitation 
by alcohol, the filtrate contains no ferment, the enzyme re- 
siding entirely in the cells. Until these are destroyed by the 
spirit, the enzyme cannot be extracted, being apparently 
unable to diffuse through the protoplasm and cell-wall. The 
same peculiarity, it may be observed, is characteristic of the 
Tornla yielding invertase, which can only be extracted after 
the death of the organism 1 . The action is an intracellular 
one only, the urea being absorbed and the ammonium car- 
bonate excreted. 
The action of the ferment of Torula Ureae is, like most 
others, one of hydration ; it seems to be concerned in the 
active life and nutrition of the plant. 
The Enzymes of Bacteria. 
In recent years several observers have been able to extract 
from various other micro-organisms, especially bacteria, enzymes 
which may be said to belong to one or other of the different 
groups described. In 1887, Bitter showed that certain of these 
forms produced some that could be separated from the microbes 
themselves. He killed the organisms by sterilisation at 6o° C., 
and ascertained that that temperature did not destroy the 
enzymes, which continued able to liquefy gelatin and to pepto- 
nise albumin. Hankin extracted from the bacillus of anthrax an 
enzyme that is capableof formingalbumoses from fibrin. Several 
toxic bodies of this class have been traced to similar agency, an 
extract prepared from the organisms being capable of forming 
them in the absence of the cells. The ordinary putrefactive 
bacteria may excrete or yield an enzyme resembling trypsin in 
1 Lea, loc. cit. 
