Green. — On Vegetable Ferments . 1 1 9 
its action on proteids 1 . Sirotinin showed that culture-fluids that 
had been filtered through porcelain could still liquefy gelatin. 
The same microbe may secrete more than one enzyme, the 
preponderating formation depending on the nature of the 
medium in which it is cultivated. Thus Lauder Brunton and 
MacFadyen 2 isolated two such bodies from the same microbe, 
one of a peptonising nature appearing most prominent when the 
bacillus was cultivated in meat broth, and a diastatic one when 
the culture-medium was starch-paste. These were two enzymes, 
and not one with both powers ; the former being most easily 
extracted. Acid favoured and alkalis impeded its activity. 
Wood 3 also identified two enzymes in each of four microbes. 
These were Koch’s cholera-bacillus, Deneke’s cheese-bacillus, 
Finkler’s cholera-nostras-bacillus, and Miller’s bacillus. The 
two enzymes were a peptic and a rennet ferment, and were 
prepared from sterilised culture fluids in which the various 
microbes had grown. Wood found that the enzymes from the 
different bacilli varied a good deal in their power of resisting 
the influence of acid media, those from Koch’s bacillus being 
destroyed by very little acidity, while those from Finkler’s and 
Miller’s bacilli could act in distinctly acid solutions. The two en- 
zymes themselves showed a different power of resistance, a coa- 
gulation of casein occurring when peptonisation was completely 
inhibited. With carbolic acid the effect was exactly the reverse, 
the rennet being destroyed before the proteo-hydrolytic one. 
Wood noticed that the bacilli themselves showed a varying sus- 
ceptibility to acids exactly corresponding to that of the enzymes. 
When the cholera-bacillus is cultivated on starch-paste, it 
can liquefy it and form sugar, but this power is not like that 
of coagulating milk and peptonising proteid, as it cannot be 
extracted from the cells, appearing to reside wholly in the 
protoplasm. Wortmann 4 has ascertained that certain bacteria 
1 Hiifner, journ. f. prakt. Chem. Bd. V, 1872, S. 872. Hermann, Ztschr. f. physiol. 
Chem., Bd. XI, 1887, S. 523. Salkowski, Ztschr. f. Biol., Bd. XXV, 1889, S. 92. 
2 Proc. Roy. Soc. XLVI, 1889, p. 542. 
3 Laboratory reports, Roy. Coll. Phys., Edinburgh, vol. II. 
4 Wortmann, Zeitschr. f. Physiol. Chem. VI, 1882, p. 287. 
