The determination of sex in animal development / by John Beard.

  • Beard, John, 1858-1924.
Date:
1902
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Licence: In copyright

Credit: The determination of sex in animal development / by John Beard. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    many theories of sex, leanings towards metaphysics — a subject, which is the very antithesis of morphology. In possessing a morpho- logical basis the new features to be recorded concerning sex differ i n toto from previous explanations. The present account merely points out the material basis of what we term “sex”, and in itself it does not pretend to furnish indications how this can artificially be controlled or modified1). Anything of this nature is, of course, a question for physiology, and not for morphology. Whilst I was engaged in putting together an account of my results, two publications, the one botanical, the other zoological, appeared. Weismann’s writing treats of the determination of sex in the partheno- genetic development of the bee’s egg, Strasburger’s with the like question in dioecious plants. The results and conclusions of both observers will be referred to in the sequel. Without attempting to give an account of previous inquiries and theories, one matter must be brought forward. The investigator owes a debt of gratitude and recognition to those, who have gone before him. His debt is all the greater, when the interval of time between their work and his own is a long one. And it still exists, when in any way — even in the enunciation of an idea — they may have anticipated something in his results. Between the present writing and suggestions allied to the con- clusions contained iu it there lies an interval of nearly fifty years! In 1854 Dr. Bernhard Schultze2) from the consideration of the phenomena presented by double monsters aud like-twins rightly drew certain conclusions. His results (p. 527) include: “All double monsters arise in one egg.” “In a single mammalian egg there invariably develops only the one sex, male or female.” 1) At the same time I would insist, in agreement with Stras- burger (in: Biol. Ctrbl., V. 20, 1900, p. 785), that to all appearance any alteration of the relative numbers of the two sexes experimentally is an impossibility. In the present writing the experiments of Yung, Born, Maupas, Mrs. Treat, and others have received no mention, because at the best their researches only prove what percentage of either sex will survive under given conditions. 2) Schultze, B., Ueber anomale Duplicitat der Axenorgane, in: Arch. path. Anat., V. 7, 1854, p. 479—531, 1 pi.