162 BOAED OF AGRICULTURE. 



a highly vascular layer which is united with the stroma of the 

 ovary by a rather loose connective tissue. This membrane is 

 composed of undeveloped, nucleated, formative tissue, inter- 

 mixed with numerous, mostly fusiform, formative cells. 

 Secoud, an epithelium lines the entire follicle, and -on the side 

 looking towards the surface of the ovary, where the ovum is 

 situated, presents a wart-like thickening projecting towards 

 the interior and enveloping the ovum. In this germinal 

 eminence, as it is called, close upon the fibrous membrane 

 of the follicle, and, therefore, in the most prominent part of 

 it, is placed the egg (ovulum) imbedded in the cells of which 

 the eminence is composed. 



In the articulated and molluscous animals generally the ovum 

 is produced from ovaries, which have a glandular character, — 

 those of the former retaining a vesicular type ; of the latter, 

 often prolonged into convoluted tubes. 



In the ovaries of the advanced foetus and new-born child, 

 Graffian follicles are abundant, and the ovum can be seen 

 within them. According to Dr. Ritchie, there is a continual 

 rupture of ovisacs and discharge of ova taking place even during 

 childhood ; and I have myself verified this observation in the 

 ovary of a calf but a few days old. It is only as the period 

 of puberty is reached that the ova are perfectly developed 

 and capable of being impregnated. 



The number of ova which may be produced by a single 

 animal is immense. In fishes the number is simply incon- 

 ceivable. The number spawned by a single cod is stated at 

 from one to nine millions. In the herring as many as sixty- 

 eisrht thousand six hundred and six ova have been counted 

 from one fish. Among animals of the higher orders we also 

 have an ample provision. Dr. Barry calculates that the ovary 

 of the cow, at the period of puberty, contains as many as two 

 hundred millions ovisacs to a cubic inch of the stroma.* In 

 the human female the ovary may contain from thirty to one 

 hundred follicles. 



In the absence of proof, it seems philosophical to suggest, 

 that, judging from analogy, the ovum is directly the resultant 

 of cell-action ; that cells in the stroma, through a process of 

 reproduction, finally arrive at a stage where a certain inde- 



* Todd and Bowman's Physical Anatomy, p. 848. 



