122 
Green . — On Vegetable Ferments. 
pancreas, a zymogen is present in the glands of Nepenthes 
which was converted into enzyme by the action of the acid. 
The writer’s experiments on the antecedent of the enzyme 
in the resting-seed of the Lupin 1 also indicate a similar con- 
dition in the cells, though its identification is not so easy, as 
the acid treatment usually adopted for zymogen conversion is 
not available. It was ascertained to exist as the latter by a 
method adopted by Langley and Edkins 2 in their researches 
on the relation of pepsinogen and pepsin in the gastric cells. 
Inulase can be more easily shown to exist as a zymogen in 
the resting artichoke-tuber. One method of preparing an 
active ferment from the pancreas is to take the fresh gland 
containing no trypsin and to keep it for some hours at a tem- 
perature of 40° C. when it yields a considerable quantity. Some 
pieces of full-grown artichoke-tubers were treated in this way, 
being kept at 35 0 C. for twenty-four hours. An extract pre- 
pared from them then was found to convert inulin into sugar, 
while an extract made from other pieces of the same tubers 
without warming was inert. When some of this latter extract 
was warmed for a time with a solution of acid-albumin in 
•2 per cent. HC1, some ferment was developed in it, though 
less than was yielded by warming the tubers alone before 
extraction as just described. The free-acid treatment alone 
was not applicable in the case of inulase, as the quantity of 
acid needed to convert the zymogen was sufficient to destroy 
any ferment liberated from it. 
The glyceride- and rennet-ferments of the castor-oil-seed 
were also shown by the acid-method to exist in the zymogen- 
condition until the onset of germination, the former of them 
being convertible into the ferment also by the prolonged 
action of water 3 . 
Brown and Morris 4 mention that the secretion of diastase 
by the epithelium of the scutellum of barley is increased 
20 per cent, by the addition of very dilute formic acid. 
Baranetzky found that a freshly-prepared extract of the 
1 op. cit. p. 50. 2 Journal of Physiology, vol. VII, pp. 371-415. 
3 Green, op. cit. 4 op. cit. 
