158 PRINCIPLES OF PHYSIOLOGY 



that we may here be in a region where there 

 are no sudden jumps but transitional processes. 

 Even when matter has been taken up by 

 the living epithelium of the alimentary 

 canal, it has been altered. Thus protein 

 matters, as we have seen, are split up ulti- 

 mately to form bodies known as amino-acids ; 

 these, in passing through the living epithelial 

 cells, are synthetized into serum albumen or 

 other blood proteins ; these again are probably 

 modified in the protoplasm of lymphoid tissue 

 and in lymphatic bodies ; and ultimately the 

 protein matter, no longer like the same proteim 

 that it was at first, is now, in the lymph, 

 brought near the living matter of the cell. 

 Here we may assume that these prepared 

 proteins are linked on to the living matter by 

 hidden chemical affinities, and thus become 

 incorporated with it. There have been no 

 sudden leaps, but a series of processes ; there 

 is no sharp dividing line between what is dead 

 and what is living. So-called dead matter, 

 by these processes, has acquired properties 

 it did not possess before ; and so-called living 

 matter has by the process that we call nutri- 



