DR. MARTIN BARRY’S RESEARCHES IN EMBRYOLOGY. 
545 
rare instances of deviation, and by far the most remarkable which I have met with in 
stages so very early. 
36/. There is yet another species of irregularity. Ova found with the one in 
Plate XXV. fig. 196, just referred to, were duly advanced in their development, though 
the less developed ovum had kept pace with them in its passage through the oviduct/. 
368. Vesicles such as those mentioned in my last paper, l. c., par. 227, as having 
been found in the Fallopian tube, I am now enabled to state are of frequent occur- 
rence, and often measure to y These vesicles generally contain only a transparent 
fluid: granules or cells, such as those in Plate VIII. fig. 136. of my “Second Series,” 
being rarely seen. The resemblance between the vesicles in question and the thick 
transparent membrane (/) of the ovum, is too remarkable not to induce the belief 
that these objects are identical ; and the vesicles occur so frequently, that I venture 
to regard them as the remains of ova escaping from the ovary without fecundation. 
Should others — on finding such vesicles — be of this opinion, physiologists may be thus 
assisted in determining a question on which they are not agreed. 
The Chorion formed of Cells arising in the Oviduct. 
369. The observations made known in my “ Second Series” on the mode, the pe- 
riod, and the place of origin of the chorion, I now confirm. That the thin membrane 
there described, as rising from the thick transparent membrane f and imbibing fluid, 
is really the incipient chorion, was shown by tracing it from stage to stage up to the 
period when villi form upon it. There remained, however, two questions undecided, 
namely, whether the chorion is formed of cells ; and if so, whether the cells are those 
of the so-called “disc” brought with the ovum from the ovary. 
3/0. I have now to state that the chorion is formed of cells ; and that these cells 
are not those of the “disc” brought with the ovum from the ovary. 
371. It has been already mentioned (par. 345.) that after the fecundation of the 
ovum, the cells of the tunica granulosa are found enlarged, club-shaped, in contact 
with the membrane f by their pointed extremities alone, and as it were radiating from 
the ovum (Plate XXV. fig. 195. g 1 .). In this state of its surrounding cells — and 
accompanied by the retinacula, more or less advanced in liquefaction- — the ovum 
leaves the ovary. 
372. In Plate XXIV. fig. 185. is represented an ovum of 14 hours, found in the Fal- 
lopian tube at its middle part. The membrane /was invested by cells which together 
seemed to form a sort of mosaic work. On examining them closely, however, these 
cells were found at many parts to have coalesced, and this was especially the case on 
the left side (see the figure). Their appearance was very different from that of the 
cells surrounding the ovarian ovum ; the former being much more minute, and having 
t In this instance four ova were found at the uterine extremity of the Fallopian tube, and three in the be- 
ginning of the uterus ; one of the latter having been that in Plate XXV. fig. 196. 
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