NORMAL COWS' MILK. 



GENERAL DEFINITION. 



Milk is the secretion of the mammary glands, in which it is 

 produced by certain processes of diffusion from the blood, accom- 

 panied by a dissolution of the gland cells. Lactation commences a 

 few days after birth, and lasts for a period of time, the length of 

 which depends on various circumstances. C. Yon Yoit says : 

 "Milk consists of liquified cells. All mammals are, therefore, 

 carnivorse, for they sustain themselves by consuming a portion of 

 the body of their mother." 



Colostrum : The first milk yielded by a cow, either before, or 

 from the fourth to seventh day after calving, is called ' beastings,' 

 or ' colostrum. ' 



Market milk is generally the milk of several cows mixed. For 

 the examination of the milk, as it reaches our markets, this is 

 a point of great importance — many irregularities, frequently met 

 with in the milk of single cows, being thereby compensated. 



The substances composing milk are for all mammals essentially 

 the same. So is the general character of the milks. The differ- 

 ence of the various milks consists, therefore, only in the respective 

 quantities in which the constituents are present, as also in taste, 

 flavor and color. 



Physiological and other Causes Influencing 

 the Secretion. 



The period of lactation generally lasts three hundred days, 

 one cow giving during this time from six to ten quarts of milk 

 per day. When the animal ceases to give milk, we say that it 

 stands dry. 



