48 DISCHARGE OF OVA 



Fallopian tube, extended it upon a wax tablet, and opened it with a pair of 

 fine scissors, be found the four extruded ova, far advanced in the cavity of 

 the tube ; they were close together, at a distance of three inches (Paris 

 measure) from the ostium abdominale. Three of these ova had the usual 

 round form ; the fourth had an anomalous shape. All had still the discus 

 around the zona ; but it was clear that the cells of the discus no longer 

 retained their full normal appearance, but had already begun to undergo 

 liquefaction. Similar observations were made by Bischoff on a sow and a 

 rat. M. Raciborski also found an ovum in the oviduct of a bitch that had 

 been kept, during the period of heat, separate from the male. 



It is certain, then, that in mammiferous animals, as in the lower classes, 

 ova are brought to maturity and discharged from the ovaries independently 

 not only of the direct action of the semen, but also of the excitement 

 attending sexual union. The following facts and considerations seem to 

 render it almost as certain that this phenomenon of the maturation and 

 extrusion of the ova takes place periodically ; namely, at those times which 

 are marked by the phenomena of heat or rut. Before the age of pu- 

 berty, when the first period of heat occurs, no corpora lutea are to be 

 found in the ovaries ; but at this time they make their appearance, even 

 though the animal should be kept separate from the male.* Then it is to 

 be remarked, that in all the instances recorded with any degree of minute- 

 ness of Graafian follicles presenting the appearance of being recently 

 ruptured, the animals were at the time, or had recently been, in heat ; 

 and that, on the other hand, there is no authentic and detailed account of 

 Graafian follicles being found ruptured in the intervals of the periods of 

 heat. Again, the fact that female animals do not admit the males, and 

 never become impregnated, except at those periods, strongly confirms the 

 idea that ova are discharged at no other times. 



That the maturation and discharge of ova takes place normally at every 

 period of heat, although it cannot be said to be proved, is at least in the 

 highest degree probable. The instances in which the Graafian follicles have 

 been found ruptured in animals in heat are already numerous ; and it is 

 generally admitted, even by authors who deny the bursting of the Graafian 

 follicles, or at least the formation of true corpora lutea except as conse- 

 quences of impregnation, that at every period of heat in animals the 

 ovaries become turgid with blood, and that a certain number of vesicles at 

 the same time enlarge and become very vascular. \ 



It has been shown, too, by Dr. Barry, J as well as by Bischoff in his earlier 

 researches, that the ova in those vesicles which are enlarged at the periods 

 of heat, themselves present certain changes in their size and structure which 



* Sir E. Home, Phil. Transactions, 1819. 



t Cruikshank, Phil. Trans. 1797. Hausmann, Op. Cit. p. 73. Paterson, Edin. Med. & 

 Surg. Journal, vol. liv. pp. 394 and 401. 



Phil. Trans. 1832, Part ii. p. 310, par. 125. 



