872 THE PHYSIOLOGY OF REPRODUCTION. 



lems, in view of the fact that the accessory phenomena are the ones 

 which have at present the greater practical interest. 



The function of reproduction is often omitted from physiolog- 

 ical courses, and the reason perhaps is partly that the structural 

 features and the development of the embryo have been assigned to 

 the department of anatomy, and partly because it is a function 

 not essential to the maintenance of the existence and reactions of 

 the organism. The reproductive organs might be eliminated en- 

 tirely and the power of the body as an organism to maintain its 

 individual existence not be seriously interfered with. The physio- 

 logical importance of the reproductive organs lies not in their 

 co-operation in the communal life of the various parts of the body, 

 but in their adaptation to produce another similar being. We 

 may explain, therefore, the co-ordinating mechanisms of the 

 body without reference to the reproductive tissues, except so far 

 as their supposed internal secretions affect general or specific 

 metabolism. 



CHAPTER LIT. 



PHYSIOLOGY OF THE FEMALE REPRODUCTIVE 

 ORGANS. 



The Graafian Follicle and the Corpus Luteum. The functional 

 value of the ovary is connected with the formation and rupture 

 of the Graafian follicles, whereby an ovum is liberated. The pri- 

 mordial follicles consist of an ovum surrounded by a layer of fol- 

 licular epithelium. Beginning at a certain time after birth and 

 continuing throughout the period of active sexual life, some of these 

 primordial follicles develop into mature Graafian follicles and mi- 

 grate to the surface of the ovary. The change consists in a "pro- 

 liferation of the follicular epithelium and the formation of a serous 

 liquid, the liquor folliculi, between the layers of this epithelium. 

 In the matured follicle there is a connective tissue covering, the 

 theca folliculi, formed from the stroma of the ovary and consisting 

 of two coats or tunics the external and the internal. The cells 

 in the internal tunic develop a yellowish pigment as the follicle 

 grows, and are sometimes designated as lutein cells. Within the 

 capsule formed by the internal tunic there is a layer of follicular 

 cells known as the membrana granulosa and attached to one side 

 is a mass of the same cells, the discus proligerus within which 

 the ovum is imbedded. The follicular liquid lies between. This 

 liquid increases in amount, and when the follicle has reached the 



