32 VARIOUS KINDS OP MILK. 



cay under the influence of the atmospheric air. It is likewise produced 

 during digestion by the saliva, and also by the pancreatic juice. The 

 turning sour of milk on the stomach is due to the transmutation of its 

 sugar into lactic acid. 



An infant finds in its mother's milk whatever it wants for the growth 

 Physiological of its own body. In its system the curd resumes the form 

 uses of milk. O f albumen, or passes into the condition of fibrin or syntonin, 

 and in this manner its muscular and gelatinous tissues are made. The 

 butter is deposited in the adipose cells, or burned at once for the pro- 

 duction of animal heat, a part of it, however, being incidentally consumed, 

 as will be hereafter explained, in the fabrication of fibrin and for other 

 histogenetic purposes. The phosphate of lime is carried to the osseous 

 system, now in a state of rapid increase, and bone is formed from it. 



But though milk is so well adapted to the wants of infantile life, it is 

 unsuited to the adult. Its nitrogenized principle, casein, though in suf- 

 ficient quantity for the repair of muscular waste and development at the 

 former period, is inadequate to these purposes at the latter, when de- 

 struction, arising from the incessant activity of the muscular system, is 

 V ri k* d so g rea ^7 increased. It is interesting to remark how the 

 of milk for dif- composition of milk is modified when there is a necessity to 



nt animals. meet these indications, its nitrogenized principle being in- 

 creased in the case of animals such as the cow and horse, the young 

 of which commence locomotion almost at birth, or at a far earlier period 

 than the human infant. This excess of casein is necessary for the re- 

 pair of the resulting waste. 



The Constitution of Mlk. 



This table presents an explanation of the unsuitableness which is 

 sometimes remarked in the milk of the cow when used for the nourish- 

 ment of children. Milk which is adapted to the wants of the calf is not 

 adapted to the functional wants of the child. Experience has taught the 

 nurse that these difficulties may in part be removed by diluting it with 

 water and sweetening it with sugar, the effect of this being to -reduce the 

 percentage of the nitrogenized element, the- casein, and to increase that of 

 the respiratory, and so approximate the composition more closely to that 

 of human milk. 



Moreover, milk is not suitable as the sole nourishment of adult life, 

 since it does not contain in sufficient quantity those phosphorized com- 

 pounds which are necessary for the repair of the waste of the cerebral and 

 nervous tissues, which at this period are much more active than in infancy. 



