104 PHYSIOLOGY AT THE FAKM. 



in milk are chlorides of potassium and of sodium, phosphates 

 of the alkalies, and a certain proportion of soda and potash, 

 which are combined with the caseine and render it soluble 

 besides phosphate of lime, and, perhaps, phosphate of mag- 

 nesia ; there is also a notable proportion of oxide of iron. 



As the body of the calf undergoes a very considerable in- 

 crease in bulk and weight when the sole food afforded is the 

 mother's milk, every element which enters into that increase 

 must be derived from the milk consumed in the mean time. 

 The sugar and butter of the milk, besides the uses which they 

 probably serve in the processes of digestion, afford materials 

 for the maintenance of animal temperature in the eremacausis 

 which takes place in connection with the function of respiration. 

 The caseine alone can provide materials for the augmentation 

 of such solids as the muscular frame and the nervous system. 

 As remarked when speaking of the nutrition of the foal (p. 48), 

 the caseine having much the same ultimate constitution in re- 

 spect to oxygen, nitrogen, carbon, and hydrogen, as albumen and 

 fibrine, it is not difficult to believe that it passes into one or other 

 of these under the operative influence of the living body, and 

 though caseine be deficient in the phosphorus which albumen 

 and fibrine severally contain, yet that the requisite phosphorus 

 may be obtained by the deoxidation of phosphoric acid derived 

 from the phosphates found in milk. The phosphate of lime 

 and the phosphate of magnesia, both of which have been de- 

 tected in cow's milk, account for the increase of the skeleton 

 while the diet of the young animal is confined to the mother's 

 milk. Among the substances present in living bodies in very 

 minute proportion is the fluoride of calcium. There is little 

 reason to doubt that this substance will be found in cow's 

 milk as well as the other constituents of bone. 



It was already noticed that, during the digestion in the calf, 

 the milk is conveyed, after deglutition, straight into the fourth 



