THE OVUM IN THE AMPHIBIA. 
237 
Segmentation took place only, in two or three ova, at four hours and twenty-four 
minutes, and at the end of ten days only three embryos had been produced. 
(b.) Starch. No. 10. p.m. 1** 40“ . — One hundred and fifty-eight ova were passed 
into a solution of starch in water, and at the end of ten seconds one-half of the whole 
quantity of seminal fluid, obtained from a single frog, and previously mixed with 
water, was added to them. 
After the ova had remained in the solution and been gently agitated during twenty 
minutes, they were carefully washed and removed to clear water. 
At four hours and twenty-six minutes only a very few of these ova, not more than 
eight or ten, had become segmented, notwithstanding the large quantity of recent 
impregnating fluid that had been added to them. At the end of ten days oiAyfve 
embryos had been produced. 
It was remarkable that very few of the ova in this experiment cohered together, as 
the frog’s ova almost invariably do when placed in fluid. On the contrary, most of 
them remained separate and isolated, although their envelopes had imbibed water and 
expanded to their usual extent in a similar space of time. 
No. 11. P.M. 1^ 47“. — Seventy-one ova were passed on a perfectly dry surface, and 
immediately afterwards were covered, by means of a hair-pencil, with a thick solu- 
tion of starch, and at the expiration of ten seconds with impregnating fluid, and water 
was quickly added. 
The water was changed at the end of fifteen minutes. At four hours and twenty- 
five minutes, only two or three ova had become segmented. At the end of ten days 
three embryos had been produced. 
The concluding experiment with starch was the counterpart of No. 5, with gum. 
No. 12. P.M. !*> 44“. — One hundred and nineteen ova were passed into water, with 
which one-eighth part only of the seminal fluid, obtained from the Frog, had already 
been mixed. Twq seconds afterwards a solution of starch was added to these ova, 
and at the end of sixteen minutes they were removed to clear water. 
In four hours and twenty -six minutes segmentation had commenced in many of these 
ova. The exact number I omitted to ascertain. But the change had taken place in 
a much shorter space of time, and was more general, although scarcely one-fourth 
part of the quantity of seminal fluid that had been employed in No. 10 was used in 
this case. Nevertheless, in ten days twelve embryos had been formed. 
This experiment, therefore, was quite confirmatory of the conclusions drawn from 
its counterpart. No. 5, with gum, and Nos. 10 and 11 as fully bore out those deduced 
from Nos. 1 to 5, with the same ; while the entire set seem to be in full accordance 
with the already arrived at conclusion, that fecundation is commenced almost imme- 
diately the fecundating body is in contact with the ovum. Thus, then, with regard 
to the nature of impregnation, we seem to have obtained sufficient proof that the act 
is effected through the agency of the spermatozoon, and not through that of the liquor 
seminis, as was formerly supposed. 
