THE SECRETION AND PROPERTIES OF MILK 1389 



The fitness of caseinogen for building up the tissues of the body is 

 evident when we compare the products of its hydrolysis with those 

 of all the proteins in other food-stuffs. It will be seen that practically 

 every amino-acid and allied substance employed in the building up 

 of the various proteins is represented in caseinogen. The only 

 exception is glycine, which can be easily formed from other amino- 



acids. 



CHEMICAL CONSTITUTION OF DIFFERENT PROTEINS 



In another point we find an adaptation of the milk to the growth 

 of the young animal, and that is in its lecithin content. Lecithin 

 is probably employed to the largest extent in the building up of 

 the central nervous system, where it forms the most important 



