276 MR. NEWPORT ON THE IMPREGNATION OF THE OVUM IN THE AMPHIBIA 



It may be matter of surprise, that, considering the immense quantity of spermatozoa 

 which exist even in a microscopic drop of fluid, and considering' also the abundance 

 which come in contact with the surface of the egg, even when but a small quantity 

 of fluid is employed, as in artificial impregnation, a much greater number do not 

 penetrate jthan are usually observed to do so. There are conditions and circum- 

 stances which affect this result. Thus I have found, in repeated observations, that 

 only those spermatozoa which, at the moment of first contact with the egg-enve- 

 lopes, are in rapid action, and have their body portion directed, either perfectly 

 centripetally towards the yelk, or at angles but slightly inclined to it, do by any 

 possibility enter ; while those which happen to be directed horizontally to the 

 surface of the egg at the instant of contact, always adhere to it laterally, and lose 

 their power of motion, but do not penetrate ; and the like also is the case with 

 those which become attached by their caudal end, and even with many which 

 adhere by their thicker end, when they come into contact with the egg at very 

 acute angles. Further, I have noticed, that a relatively much greater number of 

 spermatozoa penetrate the envelopes when supplied to the egg immediately after 

 this has been removed from the female into water ; especially when the spermatic 

 fluid also has been recently passed from the male ; and more decidedly so when 

 passed from a male in full season, at which time the movements of the spermatozoa 

 are most energetic. Thus the chances of penetration through the envelopes, and 

 consequently of fecundation of the egg by the spermatozoon, are in direct relation to 

 these circumstances; and inversely to those of an opposite character, being less in 

 proportion to the length of time the egg has been removed from the female, or the 

 fluid from the male ; the healthfulness of the parent, and consequent power of motion 

 in the spermatozoon ; the temperature of the season, and the quantity supplied to 

 the egg. 



These were the conclusions deduced from the previous observations, and they have 

 been fully borne out by subsequent experiments, some of which have been made in 

 the presence of my friends Professors BELL, BOWMAN, CARPENTER, and Mr. BUSK, 

 Fellows of the Royal Society, and Professor ELLIS, who permit me to mention the 

 circumstance. 



Narcotization of the Spermatozoon. I may now mention some experiments which 

 were made with the view to test the fecundatory influence of recently obtained sper- 

 matozoa when narcotized by chloroform. These experiments were suggested by a 

 communication made to me by Mr. BUSK, F.R.S., who, after witnessing my mode of 

 procuring the eggs of the Frog, conceived that a similar result might be attained by 

 narcotizing the gravid animal without killing it, as is necessarily done in my experi- 

 ment ; and on putting this opinion to the test he found that it may be accomplished 

 with ease and success. It then occurred to him to try the effect of exposing the 

 spermatozoa to the vapour of chloroform, by simply covering the spermatic fluid 

 contained in a watch-glass covered with blotting-paper wetted with the liquid, 



