83 



time of impregnation; and that the spermatozoon does not pene- 

 trate into, but only lies in contact with the envelopes. 



He next gives the results of some exj3eriments with solution of 

 potass, in confirmation of his former observations ; and further shows, 

 the effect produced on the egg by immersion in solutions of potass 

 and soda, with different proportions of the salts ; and afterwards details 

 the results of other experiments made to test some of the more re- 

 markable ones by Spallanzani with regard to the effect of very minute 

 quantities of the impregnating fluid. In these trials the author has 

 proceeded by the mode of direct application of the fluid, and not by 

 immersion of the eggs in large quantities of water, with small propor- 

 tions of seminal fluid, the mode followed by Spallanzani. The result 

 of the direct application through contact, once only with each egg, 

 with the point of a pin v>'etted with the fluid, was, that this was 

 sometimes sufficient to effect the commencement of segmentation, 

 and consequent jo^r^za/ impregnation \ while, if the fluid was allowed 

 to drain off the pin, by continuing the contact for a few seconds, 

 then complete segmentation, and full impregnation follov/ed, and, 

 other circumstances being favourable, an embryo was produced ; and 

 when the head of a pin was employed to apply the fluid, then the 

 usual result was full impregnation ; so that these results confirm 

 those by Spallanzani. The author further states that it appeared to 

 be of no consequence as to which surface of the egg was touched, 

 the dark surface, light surface, or the side, — the result was the 

 same. 



He next proceeds to show, that when the egg is immersed in pui^e 

 seminal fluid a directly opposite result e?isues. Segmxcntation then 

 seldom occurs, and the embryo is but rarely produced ; and further, 

 that the effect then produced on the egg is very similar in appear- 

 ance to that of the chemical action of solution of caustic potass ; the 

 yelk becomes shrivelled and decays. These results he thinks are 

 not explained by the views at present entertained respecting the 

 nature of impregnation. The author then refers to the observations 

 made by himself, and also by M. Quatrefages, which tend to show 

 that no impregnation is effected, even by the contact of the sperma- 

 tozoon with the egg, when all motion in the spermatozoon has entirely 

 ceased ; and he conceives that this fact, when considered with the 

 results now obtained, leads to a new view of the subject. 



Reference is then made to the views of Faraday, Mr. Grove, Mat- 

 teucci, and others, respecting the correlations of the physical forces ; 

 and the author mentions that the relations of the vital to the physical 

 forces were referred to by himself in 1845, and also in the same year 

 by M. Mayer, and that his object now is to apply these views to the 

 investigation of the function of impregnation. He thinks that im- 

 pregnation is commenced, if not entirely completed, by what may 

 possibly prove to be a new condition of force, i7i, and peculiar to, 

 the impregnating agent, the spermatozoon, wiiich he designates 

 sperm-force^ and distinguishes from the force of growth and develop- 

 ment in cells, through which the spermatozoon is produced. He 

 further distinguishes it from the force of muscular contractility ^ and 



