234 
MR. NEWPORT ON THE IMPREGNATION OF THE OVUM, AND 
in a running stream, and in a natural state, they would come to maturity, and this 
difference appears to be owing to the more perfect aeration of the water in the natural 
than in the artificial development. 
There is a certain condition of the envelopes of the egg, of not very unfrequent 
occurrence, which affects the impregnation. In this condition the envelope is semi- 
opake and thickened, and the alteration is induced I suspect by too long retention 
of the ova in the oviduct during a period of excitement : this pathological state 
seems interesting, as it may have its representative in the ova of other animals, and 
may be operative in like manner in them. 
On the 15th of March, 1853, I employed in an experiment a pair of frogs that had 
been in constant union since their capture eight days before, and on passing the eggs 
in the usual way I noticed (what I had before observed) that the envelope was more 
opake or clouded, thicker and more irregular than usually. On fecundating the eggs 
with recent healthy sperm 1 found the changes were slower in their occurrence, and 
the number of embryos formed was much smaller than in experiments on eggs with 
healthy envelopes. Thus out of fifteen eggs in separate cells, not more than a third 
were fecundated ; and in these, at a temperature of 60° Fahr., the chamber could not 
be perceived with a lens till after the lapse of an hour and ten minutes, instead of less 
than an hour; and segmentation of the yelk did not begin for three hours and fifty- 
five minutes at a temperature of 60° to 65° Fahr., instead of at about three hours and 
twenty minutes. 
The results were still more marked in two other sets of eggs, fifty in each, where a 
smaller quantity of spermatozoa was employed, and more time occupied in making 
the experiments; for in the one set, only three or four eggs were segmented with but 
one embryo; and in the other set, a very few underwent segmentation, and but three 
embryos were afterwards produced. 
These and other experiments show that the unusual condition of the egg affected 
the process of fecundation, and that to this cause the failure in the production of 
embryos is to be attributed. And as the act of fecundation is accomplished through 
the motor power or force of the spermatozoon, by which that body is enabled to pass 
through the coverings of the healthy egg, it appears that, when there is any deficiency 
in the usual power, arising from an unhealthy condition of the fertilizing body, or an 
increase in the resistance in the yelk coverings, the spermatozoon is unable to pass 
through the membranes into the yelk, and the egg remains unfertilized. 
Of the spherical bodies which appear on the Yelk after fecundation. 
1 have already alluded* to the presence of certain spherical bodies, which appear 
within the clear chamber of the egg of the Frog, and on the surface of the yelk sub- 
sequent to fecundation. Like bodies have been noticed, especially in the Gastero- 
podous Mollusca, among the Invertebrata, and have been even seen in some of the 
* Philosophical Transactions, 1851. 
