228 MR. NEWPORT ON THE IMPREGNATION OF 



of time, than can always be done when alone and unassisted. It was evident that a 

 proper understanding of the nature of the act of impregnation, if ever this becomes 

 known, will be led to chiefly by attention to the periods of time in which it is effected. 

 I obtained therefore the assistance of a friend, to note the spaces of time which 

 elapsed in each stage of the following experiments, so that these might be performed 

 with the quickest dispatch, and the attention of the experimenter be not withdrawn 

 from each until it was completed. 



Set Q. March 30, 1850. Atmosphere 49 FAHR. 



The seminal fluid employed in this set of experiments was not obtained from the 

 usual source. From some cause or other it could not be so procured. I therefore 

 killed a male frog, by dividing the spinal cord in the medulla oblongata, and pressed out 

 the fluid from the testes, which were gorged with spermatozoa, as found by examina- 

 tion with the microscope. From the presence of a great number of spermatozoal 

 cells, and from the water with which I mixed the fluid becoming slightly turbid and 

 albuminous, it was seen that it was not fully matured, a circumstance to be borne in 

 mind with reference to the experiments, which were commenced some minutes after 

 the fluid had been thus obtained. It was doubtful also whether the eggs were quite 

 mature. 



It is necessary further to mention, that in these experiments two solutions of potass, 

 with different proportions of the salt, were employed ; one having twenty grains in one 

 ounce of water, and which, to avoid repetitions, I shall designate " strong solution ; " 

 and the other having only eight grains of the salt in one ounce of the fluid, and 

 which I shall refer to as the " weak solution" 



No. 1. P.M. 4 h 45 m . Forty-five ova, passed on a dry surface, were bathed with 

 seminal fluid and water, and^ve seconds afterwards with the weak solution of potass, 

 and were then washed, and placed in clean water. The whole time occupied in the 

 experiment did not exceed thirty-five seconds. 



On the following morning, segmentation was found to have taken place in twelve 

 ova. This as well as the following sets of ova were then removed to a higher tem- 

 perature, in which they were allowed to remain ; but no embryos were produced. 



No. 2. P.M. 4 h 58 m . Fifty-three ova were treated in exactly the same way, but with 

 the strong solution of potass ; the interval between the application of the impreg- 

 nating fluid and the solution being only two seconds, and the whole time occupied 

 forty -five seconds. v ' 



Segmentation took place in three or four ova, but not completely. Several ova 

 also were altered in form ; but not a single embryo was produced. 



No. 3. P.M. 4 h 52. One hundred and twenty-two ova, passed on a dry surface, 

 were immediately well bathed with seminal fluid and water, and two seconds after- 

 wards with weak solution of potass, which was allowed to remain with the ova, and 

 water was then added. The whole time occupied was forty-five seconds. 



Segmentation took place in a great number of these ova, certainly from fifty to 



