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CHAPTER III 



THE PHYSIOLOGY AND SECRETION OF 

 MILK 



THIS topic is a subject upon which much has been 

 written. Milk is one of the most common products 

 of animals, and is inseparably connected with human 

 existence. It is, however, one of the most mysterious 

 products with which we have to deal. Man has been 

 able, by breeding and environment, materially to 

 change the quality and quantity of milk production. 

 He has been able to change so far the natural condi- 

 tion of the cow as to cause her to give a limited 

 quantity of very rich milk or a large quantity of milk 

 less rich in butter fat. While the character of the 

 fully developed individual cow may become so fixed 

 that she is not subject to change in quality by change 

 in feed or care, her offspring, taken at birth, may be 

 trained in such a manner as to improve both quality 

 and quantity by the manner in which it is reared. 



Milk is a product which is subject to remarkable 

 changes while in the body of the animal secreting it. 

 Fright, anger, pain all leave their traces in the milk. 

 In the human mother the first two of these have been 

 known to infuse the milk with poison, and to cause 

 convulsions, and sometimes the death, of the nursing 

 child. No doubt the same causes produce similar 

 effects in the animal mother. Experiments have 

 proved that when a cow has been milked on one side, 

 she will, after being frightened or greatly excited, im- 



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