Green . — On Vegetable Ferments . 105 
first work which calls for notice is that which was carried out by 
Reess and Will 1 of Erlangen on the leaves of Drosera ro tun di- 
folia. Working on the same lines as animal physiologists, they 
treated the leaves with strong alcohol to dehydrate them and 
then, after reducing them to pulp, they extracted them with 
glycerine. This extract, made acid with dilute hydrochloric 
acid, was found capable of dissolving swollen-up fibrin at a 
temperature of 40° C., and the resulting liquid gave the re- 
actions of peptone. Careful control-experiments proved that 
the power was due to the presence of a soluble enzyme. In 
1876 von Gorup-Besanez 2 demonstrated the existence of a 
similar body in the pitchers of Nepenthes , and his results 
were confirmed and extended by Vines 3 a little later. Since 
that date proteohydrolytic ferments have been discovered in 
several plants and have been more critically examined. 
Writers on animal physiology have generally classified 
these enzymes into two groups ; the first, of which the pepsin 
of the stomach is representative, being capable of converting 
proteids into peptones, probably by hydrolysis ; the other, 
illustrated by the trypsin of the pancreas, carrying the diges- 
tion further, and decomposing some of the peptone into nitro- 
genous crystalline bodies, chiefly amides such as leucin and 
tyrosin. Both of these groups appear to have representatives 
in the vegetable kingdom. 
Pepsin. The members of the peptic group were the earliest 
known. Such are the ferments of Drosera , Dionaea , Pinguicula , 
and the other insectivorous plants, with probably those of the 
pitcher-plants Nepenthes , Sarracenia , &c. Our knowledge of 
the former group is due in greatest measure to the labours of 
Darwin 4 . 
The ferments in all these are secreted by the leaves, which 
are furnished with glandular structures capable, on being 
stimulated, of pouring out a peculiar secretion which possesses 
peptic powers. When an insect, or a small piece of nitro- 
1 Bot. Zeit., Oct. 29, 1875, No. 44. 
2 Berichte d. deutsch. chem. Gesellsch. zu Berlin, May 22, 1876. 
3 Journ. Linn. Soc. Bot., vol. XV, p. 427. 4 Insectivorous Plants. 
