THE CHEMISTRY OF ALBUMINS 197 



H H NH 2 

 C_C_C-0 



H 3 C' H H N)H 



This is one of the earliest known of the decomposition pro- 

 ducts of albumin, and readily crystallises in scales or nodules 

 with very characteristic appearance. 



Hydroxy-amino Acids 



Serin, a-amino-y^-hydroxy-propionic acid, 







H NH, 



HO C-C C 

 H H \ 



OH 



This acid is of special interest as being one of the chief 

 decomposition products of silk. Emil Fischer has shown 

 that it is a general product of the breaking up of albumin. 



Di-amino Acids 



There are three important di-amino acids which, according 

 to Kossel, occur in all albumins in greater or less amount, 

 and whose relative preponderance can therefore serve as a 

 means of classification of albumin bodies. These three 

 di-amino acids are termed by Kossel hexone bases, as they all 

 contain six carbon atoms, and the basic character which is 

 characteristic of all amino acids predominates. These three 

 substances are arginin, lysin, and histidin. Arginin is the 



