230 MR. NEWPORT ON THE IMPREGNATION OF 



No. 7? and one second afterwards with impregnating fluid, and water was then added 

 to them. The time occupied was 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 h 5 m . 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 only fifteen seconds. 



No. 2. Twenty-Jive ova were treated in precisely the same way with the same solu- 

 tion (which 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 h 10 m . 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 



