214 MR. NEWPORT ON THE IMPREGNATION OF 



with water before ova were passed into it. hi Jive minutes after immersion of these 

 ova, I have found large quantities of spermatozoa already adhering to the surface of 

 their then expanding envelopes. But many of them have already been coiled on them- 

 selves, and were perfectly motionless. The water still contained very many dissemi- 

 nated through every part of it, but most of them, with few exceptions, have appeared 

 to be rigid, and to have become enlarged in diameter, but not increased in length. 

 This change has appeared to be due to the hygroscopic nature of these bodies, as 

 formerly pointed out by SIEBOLD*. Possibly this nature may have some reference to 

 impregnation. Repeated observations lead me to believe that, in whatever way the 

 spermatozoa are concerned in impregnation, they do not penetrate bodily into the 

 ovum, but merely adhere to the surface. 



PREVOST and DUMAS concluded-)- from their investigations, that the spermatozoa of 

 the Triton and Frog do penetrate into the envelope of the egg ; and they state that 

 they had fecundated ova taken from the ducts of the Triton, and after the lapse of 

 three hours, having first carefully washed them to remove all that were merely 

 adhering to the surface, have made sections of the envelopes of the egg, and, with the 

 aid of the microscope, have found living spermatozoa still struggling within. Their 

 words are " Une grande quantite" d'animalcules encore mouvans, et qui semblaient 

 se debattre dans cette espece de ge!6e ou ils se trouvaient emprisonne's. On en voyait 

 partout meme au contact des membranes de 1'oeuf." Further, that they had repeated 

 this experiment on the ova of the Frog, and found the envelope penetrated in like 

 manner with spermatozoa, still moving, but not changing place. I regret much that 

 my investigations do not enable me to confirm these observations, which seem to me 

 to be due to the circumstance of these physiologists having regarded the objects on the 

 surface as being in the interior. I have many times sought for spermatozoa within 

 the substance of the egg-envelope of the Frog, at different periods between that of 

 first contact with impregnating fluid and the time when cleavage of the yelk has com- 

 menced, and have constantly found them on the surface, but have never, even in a 

 single instance, observed any appearance of them in the substance of the envelope, 

 nor anything which induced me to suspect that they penetrate bodily into it. They 

 have been present on the surface, and adherent to it, even from within a few seconds 

 after contact, to so late as the sixth hour, but have usually been motionless ; and most 

 of them have had the caudal portion folded back on the body. I was led to make 

 these observations on the egg of the Frog, before I was aware of MM. PREVOST and 

 DUMAS' views, from the circumstance of Dr. MARTIN BARRY having mentioned;}; that 

 an orifice or fissure exists in the thick investing membrane of the ovum of the Rabbit, 

 through which, at the time of impregnation, he believed the spermatozoon to enter. 

 All the observations I have been able to make on the ovum of the Frog, both micro- 

 scopically and experimentally, are opposed to the belief in the existence of any perfo- 



* MULLER'S Archiv, 1836. f Loc. cit., vol. ii. p. 133. 



+ Philosophical Transactions, 1840, p. 535. 



