452 THE PHYSIOLOGY OF REPRODUCTION 



it retains its thickness later in pregnancy. The deciduofracts 

 remaia distinct to the end, though they partly degenerate. Hence 

 it is probable that during the whole, or nearly the whole, of 

 pregnancy they exercise a phagocytic action on the maternal 



B.V. 



Fie. 114. — Transverse section through the uterus of Sorex at a stage when 

 the blastocysts are still in the oviducts. The coUed uterine glands {61.) 

 are massed together in the anti-mesometrial regions. The uterine lumen 

 (f7) is more or less j_-shaped. (From Hubrecht's "The Plaoentation of 

 the Shrew," Quar. Jour. Micr. Sci., vol. xxxv., 1894.) 



B. v., blood-vessels ; cm., circular muscle ; l.m., longitudinal muscle. 



tissues, and store nutriment which they give up to the embryo 

 in a way as yet imknown. 



Shrew. — In the shrew (Hubrecht ^) the method of embedding 

 is centric, and no decidua reflexa is formed. The yolk-sac pla- 

 centa is not so well developed as in the hedgehog. 



The attachment of the blastocyst is modified, as in Ruminants, 



' Hubrecht, " The Plaoentation of the Shrew," Qitar. Jour. Micr. ScL, 

 vol. XXXV., 1894. 



