32 GASTRIC DIGESTION OF PROTEINS 



eeschi, 93 working in Argentina, has shown that pepsin but 

 not chymosin is to be found in the stomach of certain mar- 

 supials (Didelphis) . In view of positive evidence like this, 

 indicating the duality of pepsin and rennin, the frequent 

 failure to establish such differentiation cannot, in the opinion 

 of the author, be held as contradictory ; positive results are 

 of more significance, it seems to the author, than negative 

 ones in such a matter. Identity between pepsin and rennin 

 for the present at least certainly does not seem to be proved. 

 As for the frequently expressed suggestion that the two 

 ferments may not be precisely identical but different ' l sides ' ' 

 of one single ferment, slightly different sidechains of one 

 " giant enzyme molecule, " the author confesses his complete 

 ignorance, not knowing how to proceed in attempting to 

 make an exact differentiation between different enzymes and 

 "different sidechains of some one ferment. " To use the 

 expression of a distinguished jurist, the author is not enough 

 of an expert in this matter to see even darkly. 



93 V. Ducceschi (Cordova), Arch, di Fisiol., 5, 413, 1908. 



