THE PROBLEM OF CITY MILE SUPPLIES 



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cows, dogs or man's. Some animals produce milk which contains ten 

 times as much fat as is contained in cow's milk. Thus we find proper 

 adaptation in nature of the only suitable food for young mammals. 

 Again, the composition varies in individuals of the same species or race, 

 and during the period of lactation. As the young grow older the con- 

 centration of the milk increases. When the calf begins to suck its 

 mother's milk the milk is of thinner consistency than after the calf is 

 several weeks old. It is evident from this fact that, when we substitute 

 cow's milk for human milk as food for infants, the relative increase of 

 milk components is not proportionate to the growth of the infant, but 

 to the growth of the calf. It is, therefore, preferable to feed infants 

 with mixed milk from a herd of cows rather than from an individual 



PHOTOOnAPII C 



cow. In a herd we have cows in various stages of lactation and the 

 mixture of milk results in a uniform product, which can be modified if 

 this is desired. Practical experience has proved that the composition 

 of milk obtained from a herd runs nearly the same from day to day. 



It is well known that there are differences in composition between 

 cow's milk and human milk. In human milk there is more butter fat 

 and more milksugar. The nitrogenous part, that is, the part which is 

 necessary to replace the cells of the body and enable development to take 

 a normal course, is about half the amount in human milk as compared 

 with cow's milk. The quality of these components is also different in 

 the two kinds of milk. The protein of cow's milk consists chiefly of two 

 parts, one is casein, the other lactalbumin. The latter is more readily 

 digested than the former, but is present in small proportion. Human 

 milk contains less casein and more lactalbumin than cow's milk, and 



