234 MR. NEWPORT ON THE IMPREGNATION OF 



seen in the foregoing experiments is not the case. On the contrary, duration of at 

 least some seconds of contact, varying no doubt in different tribes of animals, and, 

 apparently also, quantity of spermatozoa, seem to be essential to fruitful and healthy 

 impregnation, as appears to be shown in the Jilt rat ion experiments, Set L 3, as com- 

 pared with L 1 (p. 207). Possibly momentary contact may suffice to occasion seg- 

 mentation, but certainly with duration of contact the ovum is fecundated. 



This leads us further to inquire whether any endosmos-is of the material substance of 

 the spermatozoon is imbibed by the ovum during any period of impregnation, before 

 or during segmentation of the yelk? and whether those media which do not act 

 chemically on the spermatozoon or the ovum can arrest the agency of the former ? 

 BISCHOFF has already shown that spermatozoa are in contact with the ovum in some 

 Mammalia, the Rabbit* and Dog-f-, from quickly after the entrance of the ovum into 

 the Fallopian tube until segmentation is nearly completed, and the yelk has acquired 

 a tuberculated or mulberry-like surface. In the ovum of the Frog I have shown that 

 the spermatozoa are in like manner seen on the envelopes from immediately after 

 immersion in impregnating fluid until segmentation has commenced. In the Newt 

 we have seen that when impregnation is effected artificially, they may be recognized on 

 the surface for a much longer period, from the time of contact with fluid, until the 

 surface of the yelk has reacquired its original smoothness, a period, in my observa- 

 tions, of from thirty-six to forty-eight hours. The persistence of these bodies to a 

 period after the first evident changes in the yelk have commenced, seems to favour a 

 supposition that their function is not completed in momentary contact. Although 

 we are at present unable to trace their influence beyond what is now stated, I think 

 it can be shown that their function can be arrested by media which affect them me- 

 chanically, when submitted to such media at the moment of contact with the ovum. 



7. AGENCY OF THE SPERMATOZOA AS AFFECTED BY MECHANICAL MEDIA. 



The object of the next experiments was to learn whether the interposition of a dense 

 fluid medium, which does not act chemically on the spermatozoa, would be as effectual 

 in preventing the influence of these bodies on the ovum as in the carmine experiments, 

 the effect of which seemed to be mechanical. 



As the experiments were made at different periods, it will be seen, that although 

 on two of these occasions the temperature of the atmosphere differed, the general 

 results were similar. 



Gum and Starch Experiments. Set S. March 25, 1850. Atmosphere 48. 



(a.) Gum. No. 1. P.M. 2 h 22 m . Seventy-sir ova were passed on a dry surface and 

 were immediately bathed with a thick solution of gum-arabic, and Jif 'teen seconds 

 afterwards with seminal fluid and water, and fresh water was then added to them. 

 The whole time of the experiment was sixty seconds. 



* Entwickelungsgeschichte des Kaninchen-eies. 4to. 1842, tab. 2, Z and 4, fig. 17 to 28. 

 f Entwickelungsgeschichte des Hunde-eies. 4to. 1845, tab. 1 and 2, figs. 10 to 16. 



