142 Heredity and Child Culture 



ways insure a sufficient supply, and it is hence 

 not necessary to rely on any of the numerous 

 proprietary preparations now flooding the mar- 

 ket. 



Milk is the universal food of all young mam- 

 mals. It is the only food in nature that is com- 

 plete in itself ; it contains all the necessary ele- 

 ments for growth as well as those required for 

 heat and energy production in a most digestible 

 and absorbable form. While every species of 

 mammalian young is perfectly nourished by the 

 milk of its own mother, the food elements are 

 present in varying proportions in different 

 species, this depending largely on the rapidity 

 of growth of the offspring; hence milks of 

 one species require some alteration before be- 

 ing given to the young of another species. 



In addition to nutrition, milk has properties 

 which no other food possesses. It is fluid when 

 secreted but when taken into the body it is 

 changed from a liquid into a semi-solid sub- 

 stance under the action of the secretions of 

 the stomach. This seems to have the function 

 of training the growing stomach to utilize solid 



