richer than the milk from the weaker. The use of inferior food 

 and unhealthy water, and certain diseases, cause Uso the produc- 

 tion of an inferior milk. Particulars regarding this will be given 

 in the chapter on " Abnormal cows' milk." 



General Physical Properties. 



Milk is an opaque, white or more or less yellowish fluid. Be- 

 tween the Angers it feels greasy. It has a weak, mild, sweetish 

 taste, and flavor to correspond. The microscope reveals the 

 presence of innumerable small j^lobules suspended in a pelucid fluid. 

 Sometimes epithelial cells, gland cells and lower organisms may 

 be recognized. The specific gravity varies from 1.025 to 1.038. 



Chemical Constituents. 



I. The main constituent of milk is water, of which, on the 

 average, 87.5 per cent, is present. 



II. The albuminates of milk are, according to the latest inves- 

 tigations of Danilewsky and Kadenhausen, as f ollo\ra : 



1. Albumen, probably identical with blood albumen. 



2. Peotalbumens, which Danilewsky obtained some time since 



by peptonizing various albuminates with alkali and pan- 

 creatine. These give to casein its acid character. Albu- 

 men and the protalbumens together form the so-called 

 casein, which is, therefore, not a single body but a mix- 

 ture. 



3. Oeeopeotein, which is an albumen with albuminoid char- 



acteristics. 



4. Stnto-peotalbumbns, which, according to Danilewsky, are 



obtained from albuminates by the action of acids and 

 pepsin. 



5. Peptones, or digested albuminates, were found by D. and 



E. in the serum of coagulated milk, together with the ex- 

 tractive substances. 



Milk contains, therefore, according to Danilewsky and 

 Eadenhausen, large quantities of incompletely digested 

 albuminates which, according to their characteristics, 

 were called protalbumens and synto-protalbwnens. 



