768 
MR. H. N. MOSELEY ON THE STRUCTURE AND 
The young ovisac ( b ) is filled with the peculiar round clear cells described as existing 
in the stroma of the ovary, and with a small quantity of coarsely granular yelk-matter, 
derived probably from the granulated cells of the ovary, which are to be seen occasion- 
ally in the necks of the ovisacs in a semidisintegrated condition, appearing as mere 
aggregations of granules around a clear spot representing the nucleus. In the next 
stage ( c ) the vitelline membrane is drawn across the cavity of the ovisac, separating off 
a space containing the relatively large germinal vesicle and the small quantity of 
coarsely granular yelk which float in the clear fluid which fills the greater part of the 
cavity. The germinal spot is composed of small rounded particles, and is irregular in 
form. In the next stage ( d ) the fine granular yelk entirely fills the cavity within 
the vitelline membrane. In all the ovaries examined, spermatozoa were found attached 
in tangled groups and masses amongst the ovisacs on the exterior of the ovary, and 
apparently in some cases the long filaments of the spermatozoa penetrated the ovisacs 
with one of their ends, whilst the other was in active motion. The filaments are, 
however, so fine and hyaline, that they are difficult to follow when lying amongst other 
tissue; and the supposed cases of penetration observed may have been merely cases 
of superposition. Free spermatozoa were also met with amongst the tissue of the 
lateral bodies termed here fat-bodies ; indeed they were found first of all in this 
situation : only two were seen ; they probably commonly escape amongst the viscera. 
Spermatozoa were found in abundance in the ovaries, even in specimens containing far 
advanced embryos. The uterine portion of the oviduct is very richly supplied with 
tracheae, which appear to be more abundant in a uterus with advanced embryos than in 
one which is empty or has very early embryos. Perhaps the tracheal supply increases 
with the growth of the embryo and consequent increased development of the uterine 
wall. 
Male organs . — The male generative organs consist of the prostates, the testes, with 
their vesiculee seminales and vasa deferentia, and a pair of bodies, apparently accessory 
glands. The male organs are displayed in fig. 3, Plate LXXII., which is a drawing 
made by Mr. Wild from a dissection. The testes ( t , t) are ovoid bodies of large size, 
which, as well as their ducts, prostates, and vesicuke seminales, are of a glistening 
white colour and very conspicuous. A short but wide convoluted tube, the prostate 
(pr), surmounts each testis, and communicates with it by means of a narrowed neck, 
which springs from a spot on the somewhat flattened surface of the testis, and not 
from its apex, but is situate somewhat below that point. The vas deferens arises as a 
fine thread in the same manner from the same surface as the vesiculae seminales lower 
down, but above the inferior margin of the organ. The thread-like duct enlarges 
directly after quitting the testis, and forms a spiral coil, which probably serves as a 
reservoir for the semen, and may be called vesicula seminalis. From this coil the long 
continuation of the duct, somewhat reduced again in diameter, twisting about in all sorts 
of irregular loops and turns, passes down to the hinder end of the body. Here the duct 
of one testis passes transversely across the body underneath the ventral nerve-cords, 
