70 THE CHEMICAL CONSTITUTION OF THE PROTEINS 



and serum both hydrolysed dl-alanyl-glycine, as also the tri- and tetra- 

 peptides diglycyl-glycine and triglycyl-glycine, which proves that the 

 enzymes in the" plasma and serum are not trypsin (or erepsin) absorbed 

 from the intestine. Red blood corpuscles hydrolysed diglycyl-glycine, 

 and the splitting caused by the plasma and serum may be due to the 

 presence of the enzymes of the red blood corpuscles, either excreted 

 naturally, or produced during the separation of the constituents, which 

 was probably not quite perfect, since it is well known that there are 

 great difficulties in obtaining serum or plasma absolutely free from the 

 red colour of the corpuscles. 



