1 



310 COMPARATIVE PHYSIOLOGY. 



bulky food ; and it is also probable, as in so many other in- 

 stances, that, when the other parts of the digestive tract fail 

 when the usual secretions are not prepared or do not act on the 

 food, glands that normally play a possibly insignificant part 

 may function excessively — we may almost say vicariously — 

 and that such glands must be sought in the small intestine. 

 There are facts in clinical medicine that seem to point strongly 

 in this direction, though the subject has not yet been reduced to 

 scientific form. 



Comparative. — Within, the last few years the study of vege- 

 table assimilation from the comparative aspect has been fruit- 

 ful in results which, together with many other facts of vegeta- 

 ble metabolism, show that even plants ranking high in the 

 organic plane are not in many of their functions so different 

 from animals as has been supposed. It has been known for a 

 longer period that certain plants are carnivorous ; but it was 

 somewhat of a surprise to find, as has been done within the 

 past few years, that digestive ferments are widely distributed 

 in the vegetable kingdom and are found in many different parts 

 of plants. What purpose they may serve in the vegetable 

 economy is as yet not well known. At present it would seem 

 as though, from their presence in so many cases in the seed, 

 they might have something to do with changing the cruder 

 forms of nutriment into such as are better adapted for the nour- 

 ishment of the embryo. 



Thus far, then, not only diastase but pepsin, a body with 

 action similar to trypsin, and.a rennet ferment, rank among the 

 vegetable ferments .best known. 



A ferment has been extracted from the stem, leaves, and un- 

 ripe fruit of Garica papaya, found in the East and West Indies 

 and elsewhere, which has a marked proteolytic action. 



It is effective in a neutral, most so in an alkaline medium ; 

 and, though its action is suspended in a feeble acid menstruum, 

 it does not appear to be destroyed under such circTimstances, as 

 is trypsin. This body is attracting a good deal of attention, 

 and its use has been recently introduced into medical prac- 

 tice. , 



Very lately also a vegetable rennet has been found in sev- 

 eral species of plants. The subject is highly promising and 

 suggestive. 



