Physiological chemistry (Volume 2).

  • Lehmann, Karl Gotthelf, 1812-1863.
Date:
1855
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Licence: Public Domain Mark

Credit: Physiological chemistry (Volume 2). Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    these departments if we were to enter more closely into these obscure subjects, on which chemistry has as yet thrown no light, and which it will probably never be able altogether to elucidate. THE FLUIDS OF THE EGG. While investigations in reference to the egg and its morphological elements, its development, and metamorphosis, have led to the most brilliant discoveries in physiology, the composition and character of the animal egg and its constituents have met with little attention from the chemist, and perhaps not without reason, for other fields of inquiry, alike more accessible and more extensive, promised to yield a far richer har- vest than could be anticipated from the investigation of this subject. An inquiry into the constituents of the egg is still deficient in those prelimi- nary investigations, which are necessary for the cultivation of the sub- ject in such a manner as to correspond to the general advance of science and the present stage of histological discovery. Thus, for instance, although our knowledge of the fats is undoubtedly much advanced, and has attained a certain decisive stage, we are still wholly ignorant of many of the animal fats and of their relations to the lipoids. Our physiologi- cal inquiries have, however, shown us that the fats participate largely in promoting the growth and .metamorphosis of the egg. Considerable obscurity still attaches to the chemical investigation of the various matters containing phosphorus, which occur, as it would appear, with the same constancy in the egg as in the brain and spinal cord. We have already frequently spoken of the deficiency of our knowledge of the protein-bodies. Inquirers have scarcely ventured till the most recent times to hazard a conjecture as to the presence of other non-nitro- genous matters, as for instance, sugar, in addition to the fats in the fluids of the egg. Under the term fluids of the egg, we also usually include those fluids which are coeval with the development of the embryo, but which we shall not take into consideration in the present place, since we treat of the liquor amnii under Transudations, of the liquor allantoidis under Urine, of the vernix caseosa under Cutaneous Secretion, and of the gelatin of Wharton1 under Mucus. As the eggs of most animals are either very small or cannot readily be obtained in any considerable numbers, those of the hen and of the carp are almost the only ones which have hitherto been examined. Since, according to Gobley's investigations,2 the constituents of the eggs of both classes of animals are almost perfectly identical, we may assume 1 [The gelatin of Wharton is the limpid fluid with which the cellular tissue, that unites the vessels of the umbilical cord with the amniotic investment, is impregnated.— G. B. D.] 2 Compt. rend. T. 21, p. 766-709; Journ. do Pliarm. et de China., 3me Ser., T. 11, p. 409-417, et T. 12, p. 513; Journ. de China. Med. T. 0, pp. 67-69.