INTERNAL SECRETIONS 



105 



sucli as the sow, tlic dioestrous interval is occu})ied by what may 

 be considered as an abbreviated pseudo-pregnancy (cf. Corner), 

 brought about under the influence of the corpus Uiteum 

 " spurinm," which very shortly undergoes involution in prepara- 



Fio. 70. — Photograph of mammary tissue of virgin rabbit. The 

 mammary development is limited to a few ducts. (From Hammond 

 and Marshall.) 



Fig. 71. — Photograph of mammary glands of pseudo-pregnant rabbit 

 fourteen days after (t'strus. The rabbit had never bred. (From 

 Hammond and Marshall.) 



tion for the maturation of a new batch of follicles and a new heat 

 period. In the heifer also, as Hammond and Woodman have 

 shown, the mammary glands may be sufficiently built up to result 

 in secretory activity, a fluid containing all the constituents of 

 milk being produced even in the virgin animal (Asdell). In 

 women, as in the pseudo-pregnant lower mammal, there is a post- 

 oestrous uterine hypertrophy, with great glandular development, 



