230 
MR. NEWPORT ON THE IMPREGNATION OF 
No. y, and owe second afterwards with impregnating fluid, and water was then added 
to them. The time occupied Wei's, forty -Jive seconds. 
The result was more decided than in the experiment referred to. The envelopes 
of the ova immediately became clouded, and no segmentation took place in any of 
the yelks, some of which became shrivelled and changed in form. 
The result of the preceding experiments being doubtful as to the cause of the non- 
production of embryos, especially with reference to the first three, and the seventh 
experiments, in which many ova became segmented, I obtained some additional pairs 
of frogs from their native haunts, and within twenty-four hours afterwards, before 
they had in any way become debilitated by confinement, repeated the experiments at 
a higher temperature. 
Set R. April 3, 1850. Atmosphere 60° Fahr. 
No. 1. p.M. 3^ 5“. — Eighty-two ova^ passed on a dry surface, were touched for an 
instant only with a pencil dipped in impregnating fluid and water, and one second 
afterwards were washed with strong solution of potass, and then with water, and 
water was then added. The whole time occupied was ovXyJifteen seconds. 
No. 2. Twentyjive ova were treated in precisely the same way with the same solu- 
tion (wdiich also was employed in the following experiments) ; the interval being 
two seconds, and the whole time twenty seconds. 
Segmentation took place, but only very 'partially, in about twelve ova of the first, 
but completely in one only of the second experiment. The whole of the remaining 
ova were shrivelled and decayed ; their envelopes exhibiting the same clouded and 
refractive property noticed in the last set. At the end of five days two embryos had 
been produced- in the first experiment, and one in the second. It was thus far con- 
firmatory of the experiments with potass in Set P, that if this salt be applied to the 
envelope several seconds after the application of the impregnating fluid, and be again 
quickly removed or diluted with water, impregnation/ may already have taken place, 
and the action of the caustic will not in that case affect the production of the em- 
bryo ; especially if the experiment be made when the temperature of the surrounding 
medium is becoming increased. But if the solution be applied before the application 
of the seminal fluid, then the spermatozoa will in most cases be decomposed, and no 
impregnation follow. In either case, however, the undiluted solution acts also on 
the ovum itself within a very short period, and destroys or renders it sterile. This 
was further proved in the succeeding experiments. 
No. 3. p.M. 3** 10™. — Fifty-eight ova were passed on a moistened surface, and were 
immediately afterwards washed with the solution, and at the expiration of one second 
were bathed with seminal fluid and water; the time occupied being only fifteen 
seconds, as in No. 1. 
No. 4. Sixty-nine ova were treated in exactly the same way, the interval being one 
second ; and the whole time occupied only twelve. 
Partial segmentation had taken place in one ovum of No, 3 ; but the whole of the 
