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



female was prepared to spawn, as was proved by her having passed a few eggs ; but 

 these remained unimpregnated, and she still retained the remainder within her for 

 nearly a day, at which time the male was removed for the experiment. The employ- 

 ment of this male was thus accidental, it being the only one I then possessed. 



The fluid was applied to the eggs within a quarter of an hour of its being obtained, 

 and the eggs were at once placed in a temperature of 61 FAHR. I remarked that 

 development appeared to go on more slowly than usual, although most of the eggs 

 imderwent segmentation, and^/^lfeewof them produced embryos, which were placed 

 together in one vessel. A few days afterwards I was surprised to find that two of 

 these embryos were greatly malformed. One had a short falcated tail narrowed at 

 its base, where it was not broader than at its extremity, and the tail of the other 

 was scarcely more than a short narrow stump, so that the embryo had much diffi- 

 culty of locomotion. A few days later three other of the embryos became distorted, 

 and one of them died much altered in form at the period of absorption of the external 

 branchiae. 



These circumstances are recorded merely as simple occurrences which point to the 

 necessity for further experiment on this curious and important subject, and not as 

 results from which any very positive conclusions can be deduced. Nevertheless, I 

 may add, that I think I have before observed that embryos which have been the 

 result of fecundation with very small quantities of fluid, are usually smaller than 

 others which are produced from full and natural impregnation. 



The effect produced by immersion of the egg in pure fluid is as curious as the 

 results above mentioned obtained from minimum quantities, and at first it is less easily 

 to be understood. I can find no more expressive term by which to indicate it than 

 that of smothering, and this, perhaps, may be found to be a more literally correct ex 

 pression of the fact than at first is apparent. It has already been shown that free 

 aeration is most essential to the development of the embryo, and I believe it is equally 

 so, in a minor degree, to fecundation. Thus while the egg may be fecundated in a 

 dense fluid, composed of equal parts of seminal fluid and water, its changes usually 

 take place much more slowly than when the proportion of water is considerably 

 increased; while if it be immersed in pure fluid, and be allowed to remain in that for 

 some hours, it may still be fecundated, and its changes be commenced, but these will 

 not proceed to the full development of the embryo. If the egg when immersed in 

 pure fluid be retained in a moderately low temperature, then the development of tne 

 embryo may go on slowly for a time, but with less rapidity than when the egg is 

 freely aerated in pure water. But if, on the other hand, it be retained in seminal 

 fluid, at a high temperature, then it usually happens that although the respiratory 

 chamber be formed, as the result of fecundation, segmentation will proceed slowly, or 

 irregularly, and the embryo, which is begun to be formed, perish. That want of 

 proper aeration is in part the cause of this infertility seems to be shown in the fol- 

 lowing experiments. 



