Tlic Mammal. 135 



one of the prime sources whence have arisen the 

 altruistic tendencies of the higher Hfe. 



Often the effort of the mother to produce milk 

 for her young causes a sad depletion of her own 

 tissues, and it is not uncommon for her to yield 

 her life in giving birth to her offspring. 



The reproductive organs are extremely sensitive, 

 and while suff'ering the changes incident to mater- 

 nity are peculiarly liable to disease, so that among 

 the higher animals the great balance of compensa- 

 tion swings, and there too death stands as a menace 

 to love. 



