ACTION OP THE FEMALE. 963 



way towards the ovarium, and fecundate the ovum either before it entirely 

 quits the ovisac or very shortly afterwards, appears to be the general rule in 

 regard to the Mammalia; and the question naturally arises by what means 

 do they arrive there? It has been supposed that the action of the cilia which 

 line the Fallopian tubes might account for their transit ; but the direction of 

 this is from the ovaria towards the uterus, and would therefore be opposed to 

 it. A peristaltic action of the Fallopian tubes themselves may generally be 

 noticed in animals killed soon after sexual intercourse ; and in those which have 

 a two-horned membranous uterus, such as is evidently but a dilatation of the 

 Fallopian tube, this partakes of the same movement, as may be well seen in the 

 Rabbit; but this peristaltic action, like the ciliary movement, is from instead 

 of towards the ovaries. Among the tribes whose ova are fertilized out of the 

 body, the power of movement inherent in the spermatozoa is obviously the 

 means by which they are brought in contact with the ova ; and it does not 

 seem unreasonable to suppose that the same is the case in regard to the higher 

 classes, and that the transit of these curious particles, from the vagina towards 

 the ovaries, is effected by the same kind of action as that which causes them to 

 traverse the field of the microscope. We shall now consider the changes in the 

 Ovum and its appendages, by which it is prepared for fecundation. 



969. Up to the period when the Ovum is nearly brought to maturity, it re- 

 mains in the centre of the ovisac or inner layer of the Graafian follicle ; and it 

 is supported in its place by the "membrana granulosa," which is continuous 

 with its proligerous disk. The movement of the ovum towards the surface, 

 which has been already referred to as a part of the changes by which it is pre- 

 pared for fecundation, appears from the observations of Valentin to be due to 

 the following cause. In the immature ovisac, the space between its inner layer 

 and the ovum is for the most part filled up with cells ; these, however, gradu- 

 ally dissolve away, especially on the side nearest the surface of the ovary ; 

 whilst an albuminous fluid is effused from the deeper part of the ovisac, which 

 pushes the residual layer (forming the discus proligerus) before it, and thus 

 carries it against the opposite wall. At the same time, there is a gradual thin- 

 ning away of the various envelops of the Graafian follicle, as well as of its own 

 walls, in the situation of its most projecting part; and thus it is preparing to 

 give way at that point, for the discharge of the contained ovum. Before rup- 

 ture takes place, however, the ovisac itself undergoes a considerable change. 

 Its walls become more vascular externally, and are thickened on their interior 

 by the deposit of a fleshy-looking substance, which, in many of the lower Mam- 

 malia, is of a reddish color, whilst in the Human female it is rather of yellowish 

 hue. This substance is at first entirely composed of an aggregation of cells 

 (Fig. 244), and may, in fact, be considered as an increased development, or 

 hypertrophy, of the "membrana granulosa" or epithelial lining of the ovisac. 

 In domestic quadrupeds, this growth, which sprouts like a mass of granulations 

 from the lining of the ovisac, is often so abundant, if the ovum be impregnat- 

 ed, as not only to fill the cavity of the -p. 244. 

 ruptured vesicle, but even to protrude 

 from the orifice on the surface of the 

 ovary ; this orifice, however, subsequent- 

 ly closes ; and the contained growth be- 

 comes gradually firmer, its color chang- 

 ing from red to yellow. In the Human 

 female, however, the new formation con- 

 sequent upon impregnation is less 

 abundant ; it does not form mammillary _____ 



projections from the interior Of the Oyi- Cells forming the original substance of the Corpua 



sac, but lies as a uniform layer upon its Luteum. 



