132 Green. — On Vegetable Ferments. 
cell-wall also helps us to see a possible explanation of their 
passage, protoplasm or proteid being held to be present in its 
substance. That the protoplasm of the cell plays a part in 
permitting or preventing the diffusion we see from the two 
Torulas described, which retain their enzymes as long as they 
are living, though the latter can be extracted after killing 
the cells. 
Reactions of the Enzymes. 
But very few reactions can be quoted by which to attempt 
to identify these enzymes; indeed the manifestation of their 
activity is at present the only reliable evidence of their presence. 
From some observations Wiesner 1 made on the behaviour of 
diastase and pepsin, he gives as characteristic of ferments in 
general a colour-reaction obtained by heating them with an al- 
coholic solution of orcin in the presence of hydrochloric acid. 
Treated thus, diastase gives a bluish violet, and other enzymes 
give other colours. Further investigations into the behaviour of 
ferments with hydrochloric acid show that this reagent colours 
them differently. Thus Guignard 2 , on boiling 1 centigramme 
of various ferments with 1 cc. of the pure acid, obtains the follow- 
ing effects : diastase yields a red turning brownish, emulsin a 
violet, papain an orange-red, trypsin a greenish-yellow. 
These colour-reactions however prove not to be specially 
characteristic of the ferments. Reinitzer 3 has shown that 
dextrin, maltose, and lactose, all give similar colours, and other 
chemists have proved that the orcin-reaction is shared by 
nearly all carbohydrates, and is due to the production of 
furfurol. Udransky 4 has obtained it also from various 
proteids. Guignard, too, quotes the action of hydrochloric 
acid alone on various proteids, showing that these give 
colour-reactions much like those of the enzymes. 
Relations of Enzymes and Organised Ferments. 
To complete the discussion of ferment-action it is necessary 
to consider further the behaviour of the lower forms of plant- 
1 Sitzber. d. math.-naturw. Kl. d. k. Akad. d. Wiss. in Wien, July, 1885. 
2 Journal de Botanique, 1890, p. 393. 3 op. cit. 
4 Udransky, Zeitschr. f. phys. Chem. 1888 and 1889. 
