326 HUMAN PHYSIOLOGY 



which is cast out is called lockia. The lochia is bloody 

 during the first days, during the fifth day it is serous, later 

 on it becomes grayish. 



The breasts swell much during the second and third days 

 after parturition. The first secretion colostrum is a thick, 

 yellowish fluid, containing colostrum corpuscles (see page 

 112); at the third day real milk is secreted. The period of 

 lactation lasts about ten months, and during this time 

 menstruation does not take place. 



