PROBLEMS IN OBSTETRICS AND GYNECOLOGY 407 



I have already referred to the theory that the chorionic epithe- 

 lium produces an internal secretion, which may exercise a delete- 

 rious influence on the maternal system. Some hold that it may also 

 act as a destroyer of certain elements circulating in the maternal 

 blood which might be toxic to the fetus if it should enter the cir- 

 culation of the latter. 



