232 MR. NEWPORT ON THE IMPREGNATION OP 



Segmentation took place at a little later period in this than in the preceding expe- 

 riments. It commenced at four hours and twenty minutes, when twenty-five ova were 

 undergoing the change. This was a full proportion of impregnation as compared 

 with No. 5, seeing that the impregnating fluid had already been mixed with water one 

 hour and forty-six minutes. Twenty-Jive embryos were the result of this experiment. 



The results thus support the explanation already given, with reference to the effect 

 produced on the envelopes of the ovum being less immediate than on the sperma- 

 tozoa ; since, in this case, twice as many ova became segmented, and ultimately 

 produced embryos, as in those experiments in which the solution was applied after 

 the seminal fluid, and while endosmosis of the egg was most rapid, and when the 

 solution remained undiluted. 



The general results of this set of experiments, compared with those of the last Set, 

 Q, appear also to show that the non-production of embryos in the whole of that set, 

 after segmentation had taken place in several of the experiments, as in Nos. 1, 2, and 

 especially No. 3, with solutions of the caustic potass ; and still further, No. 7 with 

 the nitrate, may fairly be attributed to some defect in the seminal fluid or in the ova ; 

 since, if such were not the cause, and the failure had been due either to the chemical 

 effect of the media on the ova, or to the moderate temperature of the atmosphere 

 (49 FAHR.) at the time of experiment, segmentation of the yelk would hardly have 

 taken place. This supposition appears to be the more likely, when we recollect that 

 in the Set Q, and in that set only, the impregnating fluid was obtained from the testes, 

 compressed and broken down in water, that the eggs were of doubtful maturity, 

 and that this was the only set of experiments in which no embryos were ultimately 

 produced ; although, I may now mention, that greater care was taken to ensure a 

 favourable result than in most of these investigations, the ova being removed at the 

 end of twenty hours to an average temperature of 60 FAHR., were retained in flat 

 shallow dishes, and had the water changed daily. Both sets, however, Q and R, 

 seem to prove that the act of impregnation, as evidenced in the fact of the yelk be- 

 coming segmented, must take place, or be commenced very rapidly ; and, apparently, 

 almost at the instant of contact of the spermatozoon with the coverings of the ovum ; 

 as seems to be shown in the fact, that segmentation took place in many of the ova 

 when the space of time between the application of the spermatozoon, and that of the 

 solution, which previous observation (p. 225) showed was sufficient to decompose it 

 immediately, was scarcely more than one or two seconds. Thus in Q 4, and R 1, i$ 

 must have commenced in the interval of one second, even when the strong solution 

 was used ; and in Q 2 and R 2 with the same solution in two seconds. When the 

 weaker solution was used, a greater number of ova became affected in similar spaces 

 of time, as in Q 2 and 3. These experiments seem to show that the act of impreg- 

 nation had already been commenced before the application of the solution ; as, in the 

 experiments which are the converse of those now mentioned, in regard to the time 

 when the spermatozoa and the solution were applied, a different result ensued. Thus 

 when the solution was applied to the ovum Jirst as in Q 6 and R 3 and 4, and one 



