238 MR. NEWPORT ON THE IMPREGNATION OF THE OVUM IN THE AMPHIBIA 
been liberated. There were, however, some of which the contents appeared to be 
perfectly granular, and these I regarded as spermatozoal cells in the earlier stage of 
development, u * * 1 , 
The female with which this male had been paired was killed on the 4th, at the 
time the experiments were to have been commenced. It was then found that the 
eggs, like the fluid from the male, were immature. The whole of the eggs had escaped 
from’ the ovaries into the cavity of the peritoneum among the viscera, and were 
crowded together in a mass on each side, at the anterior part of the abdomen, and 
were without any gelatinous covering. A few only had begun to enter the oviduct 
on the right side of the body, and acquire their envelopes. In most of these eggs the 
germinal vesicle had already disappeared. 
The fluid and eggs of the common Toad {Bufo vulgaris) are developed in precisely 
the same way as in the Frog. On the 30th of March 1851, I examined the bodies of 
a male and female Toad for the purpose of experiment. The great efferential ducts 
and vesicles in the male were then entirely empty, no fluid having yet descended 
into them. But the testes contained a vast quantity of spermatozoal cells, some of 
which were distended by the spermatozoon, as if in the act of being liberated. But 
not a single spermatozoon was free, or showed any sign of motion. The whole were 
still immature, the caudal portion being as yet short and imperfect. 
In the female the ovaries were distended with eggs and occupied the whole of the 
visceral cavity between the intestines. The eggs were of a sooty black colour, with 
but a slight trace of the grey surface, and appeared to be nearly mature, but had not 
yet left the ovary. The germinal vesicle of a large size, circular in its outline, and 
somewhat flattened, still existed in nearly the whole of them. 
It is thus evident that the pairing of the sexes, both of Frogs and Toads, takes 
place before the semen is fully matured, or the eggs have descended into the oviducts, 
and that there is a near concurrence in the time of maturity in both. 
These facts seem to lead to the conclusion, that when, as in some of the fore-men- 
tioned experiments, the male fluid contains a very large proportion of developmental 
cells, which occasii.m its white appearance, it is not fully matured for its function ; 
that the first portions of fluid which descend into the efferential vessels are usually 
immature ; and that it is not absolutely necessary that the spermatozoa should be fuily 
formed before the cells escape from the testes. It seems fair then to infer from these 
facts that the completion of the development of the spermatozoal bodies takes place 
in the deferential vessels, or in the vesicles, perhaps in both : further, that the 
quantity of fluid produced, when too great to be contained in the ducts, may become 
accumulated in the vesicles, to be furnished at the instant it is required; and that 
there is a near concurrence in the time of maturity in the fluid in the male, and of 
the eggs in the female, the former being only slightly in advance, in regard to time, 
of the latter, at the natural period of their encounter ; a condition which perhaps 
may be necessary to the full and healthy fecundation of the whole brood. 
