24 PROFITABLE DAIRYING 



mediately thereafter yield milk from the other side 

 distinctly different in quality and percentage of fat. 

 All this we know; but how she secretes the milk and 

 by what process it is deposited in the udder the most 

 skilled physiologists have failed to inform us. 



Writers have differed widely as to the process of 

 milk production, each giving apparently good reasons 

 for his position. The fact that fright or anger may, 

 in a single minute, change the character of the milk 

 shows that the mental state of the animal exerts a 

 powerful control over it. The highly developed sys- 

 tem known as milk veins, connecting the udder with 

 the heart, shows that in some way the milk is secreted 

 from the blood. But no writer whose works I have 

 read has claimed to find any trace of the fluid known 

 as milk in the blood. The fact that the milk secre- 

 tion sometimes amounts to fifty quarts in a single day 

 shows that unless the elements which enter in the 

 milk be combined in the udder the blood would con- 

 tain traces of milk. With all the investigation that 

 has been made we must confess that we know but 

 little about the manner in which milk is secreted. 



The udder consists of two parallel glands lying 

 longitudinally with the body of the cow and sup- 

 ported by strong muscles. Its interior is composed 

 of tissue interlaced with and sustained by ligaments 

 depending from the body. The veins, milk ducts, 

 and glands are interwoven in a wonderful system. 

 Within the gland tissues are the milk cells in which 

 the fats and other elements composing milk are col- 

 lected and combined. Albumen, fat, casein, water, 

 ash, etc., are here intermingled, stored in little sacks, 

 and, at milking, excreted as milk. The cells which 



