VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. \\J 



The insufficiency of this reasoning did not escape the penetration of his oppo- 

 nents; and the immense mass of counterfacts poured out against him, like an 

 irresistible torrent, bore away the very foundation of his doctrine. This brings 

 the advocates for the necessity of the contact of semen with the ovaries into a 

 dilemma, from which they attempt to extricate themselves by contending, that fe- 

 cundation does not require the application of semen to the ovaries in a palpable 

 form ; but that there is exhaled from it a subtile fluid in a vaporific state, called 

 aura seminalis, and that the contact of this vapour is fully sufficient to impart to 

 the ovaries their due quantity of stimulus. But the opinion, even thus qualified, 

 has not passed without animadversion. There are some who cannot comprehend 

 how the tubes should perform 1 motions in contrary directions, which they must 

 do, if they first convey the aura seminalis to the surface of the ovaries, and after- 

 wards return the rudiments of the foetus into the uterus. Such a double action 

 they think is repugnant to the economy of the part, but assign no reason for their 

 opinion. They might with equal propriety deny the possibility of a peristaltic and 

 inverted peristaltic motion of the intestines, or the opposite actions in the ce&opha- 

 gus of ruminant animals, though I am persuaded very few would acquiesce in their 

 incredulity. 



The difficulties which were opposed to the conveyance of the semen by the 

 tubes, were, as we should suspect, intended to prepare the way for a different ex- 

 planation ; therefore physiologists, by a very natural transition of thought, were 

 led to suppose that the presence of semen in the vagina alone was sufficient to ac- 

 count for impregnation. To give support to this opinion, cases were adduced, in 

 which, from some anatomical peculiarities, it seemed almost impossible that the 

 fecundating fluid could be conveyed into the uterus; and yet in several of these 

 cases impregnation had really taken place. Those who hold the contrary opinion, 

 either cavil at the accuracy of the statement, or draw a different conclusion; there- 

 fore to attempt conviction by these materials would be to engage in the service of 

 forlorn hope. It remains then to try whether by a patient experimental investi- 

 gation, we can make such an accession of new facts to our present stock of know- 

 ledge, as will enable us to undo this Gordian knot. This attempt naturally leads 

 us to review the 2 points of the question, viz. Is the passage of the semen by the 

 tubes to the ovaries, essential to impregnation? If not, what other means are em- 

 ployed? If it be true that the fecundating fluid must pass by the tubes to the 

 ovaries before impregnation can take place, ought it not to follow, as a conse- 

 quence, that if, from any cause, both these tubes be obliterated, the animal so 

 affected would be barren? Or if the animal be multiparous, would not an oblitera- 

 tion on one side prevent conception in the corresponding ovary ? Now I had some 

 distant apprehensions, even before I made this experiment, that dividing both 

 tubes would produce effects equivalent to an extirpation of both ovaries, which ex- 

 perience has since proved to be well founded; for it not only destroys the power of 

 conception, but even the disposition for using the means. 



