102 THE PHYSIOLOGY OF REPRODUCTION 



degenerative changes comparable to what occur normally in the 

 pseudo-pregnant bitch (p. 98). The mammary glands also develop 

 (p. 617) and secrete milk. The entire pseudo-pregnant period is 

 somewhat less in duration than true pregnancy, which in the rabbit 



FIG. 21. Section through uterine mucosa of rabbit twenty -four days after 

 sterile coition (retrogressive stage in pseudo-pregnancy). A great 

 quantity of extravasated blood is seen. The glands are still somewhat 

 enlarged. (From Hammond and Marshall.) 



lasts thirty days. Exceptionally (as when two doe rabbits "jump" 

 one another and show sexual excitement), ovulation followed by 

 pseudo-pregnancy may take place without coition having occurred. 1 

 In the guinea-pig Stockard and Papanicolaou 2 have described a 



1 Hammond and Marshall, loc. tit. 



2 Stockard and Papanicolaou, " The Existence of a Typical (Estrous Cycle in 

 the Guinea-Pig," Amer. Jour, of Anat., vol. xxii., 1917. 



