244 MR. NEWPORT ON THE IMPREGNATION OF THE OVUM IN THE AMPHIBIA 



perature which is always most favourable to fecundation, there were no signs that any 

 change had even been commenced in those eggs which had been immersed for a longer 

 period than thirty-five minutes. But it must be borne in mind that the fluid employed 

 had been thirty-five minutes mixed with water, and consequently had begun to lose 

 some of its efficacy. The results of the corresponding experiments at the lower tem- 

 perature Atmosphere 55, Water 53 were similar, but less marked. 



On comparing the two sets of investigations, it was found that no evidence of 

 fecundation occurred in either of them, when the eggs had been immersed during 

 forty-five minutes before the impregnating fluid was supplied to them ; and that only 

 the very earliest symptoms of any influence having been communicated to the eggs, 

 after thirty-five minutes' immersion, occurred in those which were submitted to the 

 higher temperature, in the irregular contraction of the yelks ; while in each set, both 

 in the higher and lower temperature, some of the eggs, after twenty-five minutes' 

 immersion, showed unequivocal signs of partial fecundation in the formation of the 

 respiratory chamber, the result of the contraction and depression of the upper portion 

 of the yelk previous to segmentation. But in both sets there were some eggs which, 

 after fifteen minutes' immersion, had become fecundated, and produced embryos. 

 The relative number of embryos produced after immersion for this and shorter spaces 

 of time was certainly greatest in the higher temperature ; since, when the total 

 number of eggs employed in the last six experiments in each of the two sets, in 

 which only any embryos were produced, were compared with the number of embryos, 

 it was found that in the higher temperature there were severity-eight embryos from 

 five hundred and thirty-six eggs; while in the lower temperature, from six hundred 

 and two eggs, there were only seventy-six embryos. 



The period at which segmentation occurred in the fecundated eggs of the two sets 

 corresponded also with the above results. In most of the eggs fecundated in the higher 

 temperature segmentation commenced about ten minutes earlier than in those which 

 had been fecundated, and remained during the first hour in the lower temperature. 



These results seem to show, that while the eggs are more rapidly affected, they are 

 also more certainly impregnated, and the embryos produced in greater numbers at 

 a higher than at a lower temperature. But it must be borne in mind that the number 

 of eggs fecundated in these experiments can only be regarded as comparative, and 

 as mere approximations to what takes place in a state of nature, the experiments 

 having been made with fluid which had been removed from the body, and con- 

 siderably diluted with water, more than half an hour before it was employed, and 

 consequently when its efficacy had been considerably diminished. 



These facts, then, go to confirm the previous conclusions, that the organic force or 

 vitality of the spermatozoon is of shorter duration than that of the egg ; since, if the 

 results of these experiments be compared with those obtained from former ones, it 

 will be seen that the insusceptibility of the egg depends very much more on the 

 endosmic action of its envelopes after immersion in water, than on any loss of vitality : 



