Licence: Public Domain Mark
Credit: Researches in embryology. (Second series) / by Martin Barry. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![figs. 113—]17. Plate VII. figs. US. 119. 121 A. 121 B. 122. 124.), i. e. the serous lamina of authors, or the subsequently reflected lamina of the umbilical vesicle. /«- fema/to those structures, or rather internal to the lamina of tlie umbilical vesicle, which is subsequently vascular, lies, when formed, the mucous lamina-}-.—Tiiis, I apprehend, will assist to explain why observers have hitherto supposed the embryo to arise in the substance of a membrane. It is not a previously existing membrane which originates the germ, but it is the previously existing germ which, by means of a hollow process {bb'-'), originates a structure having the appearance of a mend)rane:};. T/ie Chorton, 221. When in describing the thick transparent membrane of the ovarian ovum in the First Series of these Researches (/. c. par. 52.), I stated my opinion, in unison with that of Costb and R. Wagner, that this membrane is really the chorion of ova met with in the uterus, I had not discovered the disappearance of one membrane and the coming into view of another membrane in the Fallopian tube. Such, however, is the fact, as made known in an earlier part of the present paper (pars. 174. 172.); but it is one which did not fall und(n- my notice until near the conclusion of these re- searches, notwithstanding all tiie pains that had been taken to procure a consecutive series of stages. It affords evidence that I was formerly mistaken in considering the thick transparent membrane of the ovarian ovum to be identical with the outer mem- brane of the ovum of the uterus, and the membrana vitelli [e] to be still visible, and to have considerable thickness in minute ova met with in the uterus. It is not that thick transparent membrane itself {f) which is identical with the outer membrane, or cliorion of the ovum of the uterus, but the tiiin lamina (Plate VI. fig. 104. a and jp. cho.) which M^as seen to come into view on crushing an ovum in a certain state in the Fal- lopian tube. (The membrane (e) of the minute yelk-ball, as already mentioned (par. 174.), disappears by liquefaction during the passage of the ovum through the Fallo- pian tube.) Those who are practically acquainted with the various difficulties to be surmounted in this branch of physiology, will, I think, be disposed to make allowance for this error§. We are now prepared to trace the chorion through its early stages. 222. In Plate VI. fig. 103. a and |3. is an ovum found one inch from the infundi- bulum in the Fallopian tube, at the same time that other ova in a very nearly corre- sponding state were met with not yet discharged from the ovarium. The next stage is exhibited in fig. 104. a, which presents an ovum taken from the same part of the t The mucous lamina was possibly incipient in the ovum Plate VII. fig. 118 ; and if so, it was more ad- vanced in that represented in figs. 120 and 121. X The tache embrj'onnaire, above referred to, appears to have been seen in the Rabbit by several ob- servers. An ovum figured by Dr. Allen Thomson (Edinburgh New Philosophical Journal, vol. 9.) represents it as viewed with a low magnifying power; as does also one figured by my friend R. Wagner (Beitriige, &c., Tab. i. fig. 9.), through whose kindness I had an opportunity of seeing the object itself. § The membrane / in tlie present paper everywhere denotes that which was called the chorion, and let- tered / in my First Series.](https://iiif.wellcomecollection.org/image/b2197214x_0039.jp2/full/800%2C/0/default.jpg)
