408 MR. HANCOCK ON A SPECIES OF HYDRA, 
with 1th of an inch object-glass, they were found to be of an el- 
liptical form, and to resemble spermatozoa ; tails, however, were 
not detected, though with a higher power, it is not improbable that 
they may be found; for I could not satisfy myself of their non- 
existence. 
The nature of these tubercles or sacs, is a matter of much in- 
terest. They were discovered by Ehrenberg, and described by him 
as the male organ,—the moving bodies being considered sperma- 
tozoa. Though I have not seen the original memoir on the subject. 
I think there can be little doubt of the accuracy of this opinion, 
How else can we account for the constancy of the appearance of 
these sacs? for their development at the time the eggs are being 
produced, as we shall afterwards see is the case !—for their being 
situated always on the same part of the animal ?’—for the con- 
tained gland-like body, and moving corpuscles ?—for the eruption 
of these latter bodies, and for their resemblance to spermatozoa. ? 
Having thus detected what I believed to be the male generative 
organ, I was anxious to watch the development of the egg, which 
appears to have been already described more than once; but as 
it has rarely been observed by British naturalists, I will venture 
to give my own remarks on the subject. The lower portion of 
the body, as before stated, is enlarged at the time when the male 
organ makes its appearance. On examining the enlargement, 
Pl. VII. figs. 1 & 2 6, 6, carefully, it is found to be usually 
greater on one side than the other; here it is opake and of a pale 
rosy hue, notwithstanding that the animal is faded under the 
effect of light. The opake swelling extends nearly round the 
body, the margins being generally distinct. This is the nascent 
ovum, as it appears at first ; it gradually increases in size, Pl. VIII. 
fir. 1 d, and ultimately becomes very protuberant, bulging the 
body excessively on one side: the egg, at this time, is confounded 
with its covering; but it, d, is soon seen as a rounded, somewhat 
flattened body, contained within a transparent envelope, e, resem- 
bling the general surface of the body, of which it is apparently a 
continuation. This envelope, fig. 2 6, 6, shortly opens at the 
highest point of the swelling, and the egg, a, gradually makes its 
way through the orifice, which as gradually enlarges until the egg, 
