SEX IN LIVING FORMS 127 



(d) The increase in the thickness of the mucous 

 membrane is confined to the body of the uterus; the 

 cervix is not involved. 



(e) The other sexual organs, and the system in 

 general, are influenced more or less by the menstrual 

 process. The ovaries (one or the other) increase in 

 size, due to a ripe Graafian follicle ready to burst. 

 This does not take place during the time that the mem- 

 brane swells, but at the time of the flow of blood. 



During the menstrual process we have infiltration 

 and swelling for ten days, then hemorrhage for four to 

 five days, and finally return to the normal, restitutio ad 

 integrum, for four to five days, the whole process 

 occupying about twenty days. The infiltration and 

 swelling must, under all circumstances, be looked upon 

 as the primary impulse, as the flow of blood can 

 only take place after the former has existed for some 

 time. 



As the different theories do not explain the many 

 phenomena of menstruation, especially the two factors, 

 —that the congestion and hemorrhage cause the rup- 

 ture of a Graafian follicle, or that the latter causes 

 the hemorrhage,— we must conclude that a third factor 

 plays an important part, and that this third factor is 

 the product of ovulation, — the unimpregnated ovule. 



The whole menstrual process might be considered 

 as follows: 



1. The Graafian follicle ruptures, and the ovule 

 passes down into the uterus. 



2. In the first appropriate fold of the uterine mu- 

 cous membrane (generally near the mouth of the tube), 

 the ovule is imbedded, and causes by its presence a 

 swelling of the mucous membrane; that is, the men- 

 strual decidua. 



