448 



GENERATION. 



female quadruped is opened immediately after 

 copulation, the fimbrise are frequently not 

 ob.served to be in contact with the ovary; 

 and this is found to be the case only when 

 some hours are allowed to elapse between 

 the copulation and the death of the animal. 

 Haighton never found it to have taken place 

 in the rabbit previous to nine hours after union 

 with the male, and De Graaf not even before 

 twenty-seven hours ; but observations of this 

 nature upon animals opened soon after being 

 killed, do not make it certain that the action 

 had not taken place ; for it may be supposed 

 that the adhesion between the infundibula 

 and ovaries had commenced, but was less firm 

 than it becomes at a subsequent period, and 

 that it was merely disturbed by the violence 

 of the death or rough handling of the body. 

 This is the more probable, seeing that the 

 same change of position has been observed to 

 take place before sexual union in animals in 

 the state of heat, as by Cruikshank in the rab- 

 bit, and by Haller in the sheep. In some 

 birds, particularly domestic fowls and ducks, it 

 is well known that when they are well fed all 

 the changes necessary for the formation of an 

 ovum and its discharge from the ovary may take 

 place without the concurrence of the male, and 

 in quadrupeds there is reason to believe that 

 the turgescence and change of position of the 

 generative organs above alluded to may fre- 

 quently occur independently of fruitful or un- 

 fruitful sexual union, as from excitement of the 

 generative organs in the state of heat, or as in 

 the cases observed by Haller, of ewes having 

 connection with wedders or castrated males 

 only. 



There is every reason to suppose that the 

 same changes which we have described as oc- 

 curring in quadrupeds after sexual union, take 

 place in the same circumstances in the human 

 female ; that is, that the fimbriated infundibula 

 of the Fallopian tubes are brought near to the 

 ovaries, and are made to embrace them firmly, 

 so as, lo- -receive the contents of any vesicles 

 which may burst; and that this change is 

 produced by an action which begins usually 

 during sexual union, but which may also occur 

 without any venereal orgasm. 



The ovaries, we have already stated, become 

 unusually vascular during and after sexual 

 union; but the changes in the ovary which 

 most demand our attention, are those connected 

 with the bursting of the Graafian vesicles, and 

 the discharge of their contents. In the unim- 

 pregnated female arrived at the age of puberty, 

 the Graafian vesicles of the ovary are of une- 

 qual size. Some time after sexual union, one 

 or more of these vesicles, probably those which 

 are at the time farthest advanced, undergoes a 

 greater enlargement, and from its swelling pro- 

 jects beyond the rest of the surface of the ovary, 

 and after various other changes, an aperture is 

 formed in the most projecting part of the coats 

 of the vesicle, through which its contents find 

 an issue. But before proceeding further with 

 this narrative, we must recall to the recollection 

 of the reader the nature of the ovum, which, on 

 the occasion of the rupture of one of the 



Graaflan vesicles, is discharged from its inte- 

 rior. 



The ovarian vesicles of man and quadrupeds 

 are filled with fluid, which, viewed by the un- 

 assisted eye, appears to contain only a little 

 granular and flaky matter. This fluid is coa- 

 gulated by heat, alcohol, or acids, as albumen 

 is, and also by exposure to air. The membrane 

 forming the vesicle consists of two layers, an 

 external and internal, and the whole vesicle is 

 covered also by the general peritoneal and vas- 

 cular envelope of the ovary. 



From the earliest times anatomists and phy- 

 siologists seem to have considered the ovarian 

 vesicles as the source of the offspring; and 

 many, from a sort of loose analogy with ovipa- 

 rous animals, regarded the vesicles themselves 

 as the ova in which the viviparous foetus is de- 

 veloped. The large size of these vesicles, how- 

 ever, as compared with the Fallopian tubes 

 through which the ova have to pass, and the 

 subsequent observations of De Graaf, Vail isneri, 

 and Cruikshank, as later those of Prevost, 

 Dumas, and others, who found in the first days 

 after copulation ova in the Fallopian tubes of 

 a size considerably less than the vesicles of the 

 ovary from which they had proceeded, proved 

 satisfactorily that the ovarian vesicles and ova 

 are not identical. Various conjectures were in 

 the meantime offered by different authors as to 

 the source of the ovum ; some holding it to be 

 formed by a process of secretion, others by 

 an organic union of the male semen with the 

 contents of the Graafian vesicle, and so forth ; 

 but no one ever observed the ovum itself of 

 mammiferous animals within the ovary, until 

 Baer made this important discovery in 1827, 

 by the examination with the microscope of the 

 fluid contents of the Graafian vesicle.'* 



Baer found that, in the centre of a granular 

 layer, placed generally towards the most promi- 

 nent part of the vesicle, to which he gives the 

 name of proligerous disc or layer, there is fixed 

 a very minute spheroid body, seldom above 

 5 ^jth part of an inch in diameter. The appear- 

 ance of this body he found to be constant, and 

 on examining it with attention in the vesicles 

 of the ovaries, and after their rupture in the 

 Fallopian tubes, he traced the changes it un- 

 derwent in the first days after copulation, and 

 established satisfactorily the identity of this 

 body with the ova found by previous observers 

 in the Fallopian tubes and cornua of the uterus; 

 thus proving by actual observation what had 

 before been held only from analogy, that in the 

 mammiferous or truly viviparous, as well as iu 

 the oviparous animal, the foetus derives its origin 

 from an ovum already formed in the ovary 

 before fecundation .f 



* Epistola de Ovi Mammalium et Hominis 

 Genesi. Lipsiae, 1827. 



t We have no hesitation in giving the sole and 

 undivided merit of this discovery to the indefatiga- 

 ble and talented Baer, whose observations have con- 

 tributed, perhaps more than any other single indivi- 

 dual of the present time, to extend our knowledge 

 of the early formation of the foetus. We ought not, 

 however, to omit to mention that Messrs. Prevost 

 and Dumas conceived that in two instances they 

 had perceived ova in, the ovarian vesicles of quad- 



