570 
DR. MARTIN BARRY’S RESEARCHES IN EMBRYOLOGY. 
liquefaction (par. 337.)- There was a cavity in the centre of the ovum, 
into which the germinal vesicle (c) projected. This vesicle, still glo- 
bular, seemed filled with cells, into which the free portion of the germi- 
nal spot had been resolved (see the explanation of the preceding figure). 
100 diam. (pars. 327.) 
Fig. 158. An ovarian ovum of seven hours, and measuring in diameter //"+. Its 
Graafian vesicle was of considerable size. (The membrana granulosa 
escaped nearly entire along with this ovum.) 50 diam. 
Fig. 159. The germinal vesicle (/o'" — ) °f the ovum in the preceding figure. As 
seen in profile, its form resembled that of the crystalline lens of the 
eye. 100 diam. (pars. 327- 330 and 331.) 
Fig. 160. An ovarian ovum of y-g-'", in a state nearly prepared for fecundation. It 
was taken from a Rabbit in the state of heat. The germinal vesicle ( c ) 
had become flattened, but its size (about /g-'") was less than that of the 
germinal vesicle in the ovum fig. 162. The free portion of the germinal 
spot had resolved itself into cells, and the foundations of other cells 
had come into view, arranged in concentric layers. (The altered spot 
thus fills the vesicle, and seems to keep pace with it in its enlargement 
by the origin of new cells in the centre (par. 32/.). This centre of the 
altered germinal spot is the future point of fecundation. It continues 
at the periphery of the germinal vesicle until the ovum has been fe- 
cundated, being until then directed towards the surface of the ovum, 
and towards the surface of the ovary.) In this ovum, the discs immedi- 
ately internal to the membrane /'were indistinct from partial liquefac- 
tion. The ovum presented a cavity in its centre containing fluid, in 
which were a few pale globules (par. 33/.). A sort of canal proceeded 
from this cavity to the germinal vesiple. (The cells of the tunica gra- 
nulosa had become loosened. They are not represented in the figure.) 
100 diam. 
Fig. 161. The pellucid centre of the altered germinal spot in the ovum fig. 160. 
Around this point are two concentric layers of incipient cells (pars. 
327. 328.). 300 diam. 
Fig. 162. An ovarian ovum of yy ". The Graafian vesicle containing it was large 
and vascular, and found in the same ovary as that which yielded the 
objects in the two preceding figures. The animal was in the state of 
heat. This ovum seemed still more completely prepared for fecundation 
than that in fig. 160, from which it differed in the following respects ; 
namely, the germinal vesicle (c) was larger (//"+ in its transverse dia- 
meter), and the concentric layers of more or less incipient cells in its 
interior had increased in number, from the origin of new ones internal 
to the rest (par. 327.). Liquefaction of the objects immediately under 
