MAMMARY GLANDS. 



147 



their secretion is produced ; but experiments have as yet not de- 

 termined the question. That the glands may act automatically is 



Duct and 

 alveoli. 



Adipose tissue. 



Die weib- 



FIG. 89. From section of mammary gland of nullipara (from Nagel's "Die 

 lichen Geschlechtsorgane," in Handbuch der Anatomie des Menschen, 1896). 



proved by the fact that when all the nerves which supply them are 

 divided, the secretion still continues to be formed. 



FIG. 90. Section through the middle of two alveoli of the mammary gland of the 

 dog ; condition of rest (after Heidenhain). 



The table on page 149 gives the composition of milk and other 

 food-materials, together with their nutritive value. It is from one 

 of the Farmers' .Bulletins, " Milk as Food," issued by the United 



