ATAVISM. i73 



glands, thus furnishing an excellent example of large 

 and numerous skin glands occurring in a protected 

 situation. 



It has long been established that milk-glands are 

 modified sebaceous glands, and the difference in the 



FIG. 91. The inguinal region of a Lamb, showing the cutaneous 

 recesses in its groin. 



nature of the secretion is not very great. The sebaceous 

 variety furnishes a fatty unctuous substance ; mammae, 

 a natural emulsion known as milk, consisting of oil 

 globules suspended in fluid, containing various salts and 

 a proteid body, casein, with a small but variable propor- 

 tion of albumen. 



