12 THE CHEMICAL CONSTITUTION OF THE PROTEINS 



not a primary product as has often been suggested by Fischer and other 

 observers, and if this be the case the chief argument against the above 

 structure is removed. 



The continuation of a chain, should proline be a member, can still 

 proceed if the combination take place between its imino group and a 

 carboxyl group of another amino acid. This has also been suggested 

 by Kossel. We have at present no evidence for the linking of proline 

 in this manner. 



