254 MR. NEWPORT ON THE IMPREGNATION OF THE OVUM IN THE AMPHIBIA 
This result appeared to be far more inexplicable than any I had previously noticed. 
A somewhat similar one had occurred once before, but I had attributed that to some 
imperfection in the eggs employed, an explanation which did not apply m this case, 
as effss fi'om the same female had all been fecundated in other experiments. 
Four eggs were then passed from another frog, immediately after death, each into 
a separate cell, which was filled with a mixture of two parts of water and one of 
seminal fluid, obtained only a few minutes before it was employed. Iwo of t e eggi> 
were allowed to remain in this mixture in their cells, but the others, after a ew 
minutes’ immersion, were well-washed, and supplied with pure water, and the whole 
were then placed in a temperature of 60°Fahr. At the end of four hours I found 
the surface of the first two eggs covered with an abundance of spermatozoa ; and a 
chamber had been commenced, and the upper surface of the yelk was depressed, m 
each, thus showing that some degree of fecundation had been effected, but no segment- 
ation had taken place in either of these eggs at the end o^ Jive hours mid a haf, 
although the temperature of the room had been raised during the interval from 
60°Fahr. to 67°Fahr. The sixth hour was almost completed before eithei of these 
yelks gave any indication of the probability of this change. Segmentation then com- 
menced, but in a very irregular manner. In one egg the division was not in the 
centre, but at the side of the yelk, and proceeded no further than to about one-hal 
the extent across the surface. In the other the surface of the yelk within the 
chamber merely became sulcated twice in the same direction. Neither of these eggs 
proceeded further with their changes, and of course no embryos were produced. 
The two remaining eggs did not undergo any change whatever, and consequently 
had not been impregnated. . f , . t 
Although these failures were still attributed to some immaturity of the eggs, 
began to suspect that they might be occasioned by the immersion, or smothering of 
the eggs in fluid of too great a density ; yet this suspicion appeared to be so hypo- 
thetical as scarcelv to merit consideration, when it was remembered that on a former 
occasion when I had covered eggs with a solution of gum* and afterwards applied 
the impregnating fluid to them, some of them became fecundated. I was well aware 
that Spallanzani had found in his experiments that the greatest number of frogs 
eggs became fecundated when the fluid employed was very much diluted with waterf ; 
but I did not then know that M. Quatrefages had made an observation j whic i 
completely coincided with the result obtained by myself. This acute naturalist found 
that when he employed the pure semen of the sea-worms, the Hermella and the 
Teredo, not a single egg Mms fecundated, and that when he mixed it with only a sma 
quantity of water, so as to obtain un liquide tr^s opalin,” that then only a very small 
number of eggs showed any traces of fecundation. He ascribed these results simply 
- PhUosophical Transactions, 1851, p. 236. t Dissertations, vol. ii. p. 190. 
J Annales des Sc. Naturelles, 3"“ Serie, tom. xiii. p. 129. 
