Volume 1

Researches in embryology. Ser. 1-2. / [M. Barry].

  • Barry, M. (Martin), 1802-1855
Date:
1839
Catalogue details

Licence: Public Domain Mark

Credit: Researches in embryology. Ser. 1-2. / [M. Barry]. Source: Wellcome Collection.

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    [ soi ] XV. Researches in Embryology. First Series. By Martin Barry, M.D. F.R.S.E., Fellow of the Royal College of Physicians in Edinburgh. Communicated by P. M. Roget, M.D. Sec. R.S. Received June 20,—Read June 21, 1838. It has been truly said, that “ in all the sciences of observation, the great diffi- culty generally consists in taking the first steps.” A hundred and fifty years have now elapsed since the celebrated Regner de Graaf, after a series of well-conducted observations, maintained that the ovum of the Mammalia must exist already formed in the ovary; an opinion which, after meeting with violent opposition, appears to have been nearly abandoned, and superseded by the notion countenanced by Haller, that the ovum was formed in the Fallopian tube out of a substance discharged from the ovary. A century after De Graaf had promulgated his opinions, Cruikshank arrived at the same conclusion, that the ovum was really formed in the ovary ; but he sought it there in vain. Prevost and Dumas in 1824 obtained a glimpse of something that must have been the ovum in that organ ; Von Baer in 1827 found and recognised it there. This important discovery of Baer formed an epoch in the history of development; but it was a “first step,” and the object one of extreme minuteness. It was there- fore not surprising if the excellent discoverer did not see or justly estimate all that appertained thereto ; and he said himself “ there remains yet many a thing that will become a prize” for others. Von Baer for instance did not see the germinal vesicle contained within the mam- miferous ovum ; he saw no more than a transparent space. This, however, was an oversight of the first importance, because that which gives peculiar interest to the germinal vesicle is the fact, now generally acknowledged, that it is the most essential portion of the ovum ; and besides, as in the following pages I shall have to show, this structure and its contents are the earliest that appear in the order of formation. Overlooking the germinal vesicle in the Mammalia, Von Baer supposed the ovum itself to represent, in that class of animals, the germinal vesicle of Birds-f-. Other analogies, and they are not few, which he based on this were consequently erroneous. I have thought it proper to make these introductory remarks, because of the neces- f Professor Baer called the vesicle he discovered in the ovary, not the ovum hut the “ ovulum.” If, how- ever, it can he made to appear extremely probable that the chorion or external membrane of the ovum of the uterus is a primitive part of the ovarian vesicle of Baer, it is perhaps better to call the latter an ovum, as will he done in this memoir.