COMPOSITION OF MILK. 



385 



gradations in degeneration. Only one row of finely granular 

 cells is found lining the saccules, and the cavities are filled with 

 globules of various sizes. From this it would appear that in the 

 earlier stages of the production of the secretion, the mammary 

 cells, after a long period of inactivity, are so unaccustomed to the 

 duty they are called upon to perform, that they succumb in the 

 effort, and, being unable to produce the rich secretion and retain 

 their vitality, they are cast off. Their offspring, however, after a 

 generation or two, acquire the necessary faculty of making within 

 their protoplasm all the necessary ingredients of the milk, and 



FIG. 168. 



FIG. 169. 



Section of the Mammary Gland of a 

 Cat in the early stages of lactation. (A) 

 Cavity of alveoli filled with granules and 

 glbnles of fat 1, 3, 3. Epithelium in 

 various stages of milk formation. 



Cells of Mammary Gland 

 during lactation, stained with 

 osmic acid, so as to show the 

 various sized oil globules as 

 black masses. (Cadiat.) 



discharge them out into the lumen of the saccules without them- 

 selves undergoing any destructive change. 



The influence of the nervous system on the secretion of the 

 mammary glands is distinctly shown by the wonderful sympathy 

 between the action of these glands and the conditions of the 

 generative apparatus. Further, different emotions have an effect 

 not only on the quantity, but also on the quality of the secretion. 

 Local stimulation also promotes the secretion, for the application 

 of the child to the breast at once produces this effect, partly, 

 possibly, through mental influences, but chiefly, no doubt, by 

 reflex excitation of the gland following the local stimulation. 





