DIGESTION 253 
the juice of the Fig-tree (Ficus carica), and the leaves of 
certain species of Agave. How far these are identical, or 
whether they present specific differences, appears at present 
uncertain. They are all active in faintly acid solutions, 
but the most favourable concentration appears to vary. 
The enzyme of the Kachree gourd is most effective when 
the medium is faintly alkaline, whereas that of the lupin 
seed ig inoperative.under these conditions. Too much 
stress must not, however, be laid upon this point, as the 
enzymes have not been prepared in any case in anything 
like a pure condition. 
Recently Vines has found that members of the erepsin 
class are very widespread in plants, occurring in almost all 
parts of them. His researches suggest that possibly the 
so-called trypsins are mixtures of pepsin and erepsin. 
The action of all these proteoclastic enzymes is pro- 
bably one of hydrolysis, though it is difficult to prove it by 
analysis. 
Rennet occurs in many seeds, in some cases in the 
germinating, and in others in the resting, condition. It 
has also a wide distribution in the vegetative and floral 
parts of various plants. Whether it is really proteoclastic 
in the vegetable organism it is hard to say, as the details 
of its action are unknown. It is so in the animal body. 
The enzymes which decompose glucosides, as we have 
already seen, are numerous and varied in their distribution, 
occurring in various fungi and lichens as well as in the 
higher plants. Their action may be illustrated by the 
behaviour of emulsin, which exists in quantity in the seeds 
of the bitter Almond and in the vegetative parts of the 
Cherry-laurel (Prunus Lawrocerasus). It splits up the 
glucoside amygdalin according to the equation 
C,,H,,NO,, + 2H,O = C,H,O + HCN + 2(C,H,,0,) 
Amygdalin auenva pale Glucose 
This is, as in other cases, a process of hydrolysis. Myrosin, 
another of the group, is peculiar in that it effects its 
