252 MR. NEWPORT ON THE IMPREGNATION OF THE OVUM IN THE AMPHIBIA 
first experiment, made on the 5th of April, with fluid which had been m'l" 
water about one hour and fifty minutes before, twelve eggs contamed in a single cell 
were each twice or thrice freely touched with the loaded pins-head over the centre 
of the white surface. Three of these eggs became partially impregnated, as shown 
in the formation of the chamber in each, and segmentation commenced m one of 
them, but no emhyo was produeed from either. Fourteen eggs^ in another cell were 
touched at the same time, and in the same way as the precedmg, wit t e oa e 
pin’s-head, over the centre of the Hack surface of the yelk. 7 he whole of these eggs 
produced healthy and wellf armed embryos. 
^ These experiments were repeated on the following day on the eggs of another fro , 
with fluid which had been obtained only about twenty minutes before it was employ ed. 
Fourteen eggs were each touched once only on the centre of the white surface he 
pin-head bring loaded for each egg. But not one of these eggs became fecundated, 
Lr was even one of them partially impregnated. In another cell, at the same time 
with these, Mrteen eggs were touched on the centre of the dark surface, and /mtr of 
them became partially fecundated, but only two embryos were produced. The fai 
in this experiment certainly appeared to be due to the eggs, rather than to the mode 
of attempting their fecundation. 
At the time of making this experiment I placed two eggs, each in a separate cell, 
with their white surface uppermost, and then filled the cells, the one with neariypure 
fluid, and the other with equal parts of fluid and water. Each of these eggs became 
fecundated, and underwent segmentation, although more slowly than usual, but the 
development of their embryos was not completed, as it became arrested at a parti- 
cular period, a circumstance which is presently to be explained. Yet these expeii- 
ments showed that when the egg is completely immersed in fluid its position at the 
moment has but little reference to the act of fecundation, provided the fecundatoty 
agents are present in good abundance. A further trial was made on the 9th of April, 
when sir eggs, placed in one cell, were each twice touched on their white suiface, le 
pin’s-head being loaded each time it was employed. But neither of “'ese egf® P™" 
duced an embryo. Six eggs, placed in another cell, were also twice touched, i ^e e 
preceding, on their dark surface. The whole of these eggs became fecundated, but 
ln\y five embryos were sufficiently matured as to leave their envelopes. The flu d 
employed in these two experiments had been mixed with water aboatfifty five minutes 
before it was applied to the eggs, and consequently was becoming sligit y e eiio- 
* 
The conclusion which seems to be deducible from a comparison of these experi- 
ments is,— that when the egg of the frog is completely immersed m water charge 
with the feciindatory agents, or to which these are supplied quickly after t m iimnei- 
sion of the egg, as in the natural fecundation of the species, the actual position of 
egg at the moment of its encounter with the spermatozoon, has but little reference 
to the act of fecundation, every part of its surface having then an equal chance of 
