196 MR. NEWPORT ON THE IMPREGNATION OP 



attended to, and I noticed a curious fact which I first remarked in experiments in 

 1849. It is what I may designate partial impregnation, and is indicated by a por- 

 tion only of the yelk becoming segmented. This frequently happens with ova that 

 have been brought into contact with only very small quantities of seminal fluid, and 

 but for short spaces of time, as in some of the following experiments. These ova, 

 so far as I have observed, never produce embryos. Segmentation is arrested in some 

 at the very commencement (Plate XIV. fig. 11), in others it goes on to the second or 

 crucial fissure, and in a very few cases may proceed somewhat further (fig. 12), but is 

 never completed to granulation of the yelk. This, I think, is a fact which deserves 

 some consideration with reference to the formation of the embryo. 



Set F. March 22, 1850. Temperature of the room at the time of the experiment 

 was 48'5 FAHR., and that of the water employed 46-5 FAHR. As the proof of impreg- 

 nation is the segmentation of the yelk, and as my object now was to observe the effect 

 of small quantities of impregnating fluid applied only for very short periods of time 

 at a low temperature of the surrounding medium, it is not of consequence that this set 

 was not watched to the full development of the embryo. To show the degree of sus- 

 ceptibility of the ovum under the combined influence of these circumstances, it was 

 sufficient to attempt the impregnation at a low temperature, and after the lapse of an 

 interval to remove the ova to a room of the same, or nearly the same temperature as 

 in the set E. This was done at the end of one hour and a half. 



No. 1. A.M. 12 h 12 m . Fifty-one ova, passed on a dry surface, were each touched 

 lightly and quickly, once only, with a small hair-pencil dipped in impregnating fluid 

 mixed with water, at eleven minutes after it was obtained, and water was then added 

 to them. At the expiration of one hour and a half they were removed to a room of 

 the temperature of 59 FAHR. Segmentation did not occur until the expiration of six 

 hours and a half, and at the end of eight days only four embryos had appeared. 



No. 2. A.M. 12 U 20 m . Forty-two ova were immersed in water for Jive minutes, and 

 then exposed, and touched for an instant only as above, and again placed in water. 

 The impregnating fluid had now been obtained nineteen minutes. Segmentation com- 

 menced in some of these at six hours and three quarters, but nearly all of them 

 were only partially impregnated, and not a single specimen produced an embryo. 



No. 3. A.M. 12 h 19 m . Fifty-eight ova immersed in water for Jive minutes, were ex- 

 posed, touched for an instant as above, and again immersed for one minute, after 

 which, they were well rubbed in the water with a clean pencil, and fresh water then 

 supplied to them. The fluid employed had been obtained twenty-three minutes. 



Not a single egg gave any signs of having been impregnated, either perfectly or 

 partially, nor did a single ovum produce an embryo. 



No. 4. A.M. 12 h 23 m . Forty-two ova were passed into a solution of carmine (the 

 pigment employed by water-colour painters) for Jive minutes, and were then washed 

 with water, touched for an instant, as above, with impregnating fluid at twenty-seven 

 minutes after it was obtained, and water then supplied to them. Not a single egg 



