4 DR DAVY ON THE IMPREGNATION OF 



vided with folds, — a somewhat valvular structure, that reminds one of the mouth 

 of the common gall-duct in man, — allowing a free passage to a probe downwards, 

 but not in the opposite direction, and being amply provided with mucous fol- 

 licles, forming a provisional mucous duct, the better adapted to the descent of 

 the ova.* In the male, the testes terminate in a common duct, slightly promi- 

 nent within the verge of the anus, — the projection so small as hardly to deserve 

 the name even of papilla, very much smaller than that of the female, and neither 

 vascular, so far as I could ascertain, except in the ordinary manner, nor provided 

 with any follicles, such as usually belong to the part destined for the purpose 

 supposed. 



Further, if attention be given to the manner in which the male and female 

 fish behave during the spawning time, I think we shall have confirmation that 

 there is no act of intromission, — which indeed, anatomically considered, it may 

 be presumed there cannot be, — but also that there is no attempt made favour- 

 ing the notion that the spermatic fluid is injected (as would be necessary for the 

 impregnation of the ova) into the cavity of the abdomen of the female. That 

 the fish in the act of spawning sometimes come in contact, pressing against each 

 other, and thereby aiding the expulsion of the ova and milt, cannot, I think, be 

 doubted. By many observant fishermen, poachers addicted to the taking of the 

 fish at the time of their spawning, I have been assured of the fact from their own 

 observations ; but this is very different from the act of copulation as performed 

 in other classes of animals in which impregnation is effected before the expulsion 

 of the ova ; but though so dissimilar, perfectly suitable to the end required, and 

 quite in accordance, as we have proof in the artificial process, with the neces- 

 sary requirements. 



It is an axiom that nature does nothing in vain ; it is not less true that na- 

 ture is perfect in her works, as regards the adaptation of means to ends. In no 

 part of the animal economy is this more strongly and happily illustrated than in 

 the generative system of organs, diversiform and varied as they are in the several 

 classes of animals. Consistently, then, were the mode of impregnation that 

 which has been asserted, we may be sure that an organization, — an apparatus 

 would have been provided suitable to it. Also, as I think consistently with the 

 hypothesis, we might expect occasionally to find ova in the cavity of the abdo- 

 men, bearing marks, if they had been impregnated there, of incipient develop- 

 ment, according to the analogy of extra uterine fcetal growth sometimes witnessed 

 in the Mammalia ; but none have been described, that I am aware of, as ever 

 observed. In spent fish, that is, those which have spawned, in the instance both 



* The closure of this aperture, after the exclusion of the ova, from such observations as I have 

 made, appears to take place slowly, requiring many weeks for its accomplishment, and when effected, 

 by so delicate a medium as to be easily ruptured. To be properly examined, the fish should, after being 

 opened, be placed under water, and the blow-pipe be used before the probe. 



