Recent advances in the physiology of motion, the senses, generation, and development. Being a supplement to the second volume of Professor Muller's "Elements of physiology". / by William Baly and William Senhouse Kirkes.
- Date:
- 1848
Licence: Public Domain Mark
Credit: Recent advances in the physiology of motion, the senses, generation, and development. Being a supplement to the second volume of Professor Muller's "Elements of physiology". / by William Baly and William Senhouse Kirkes. 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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![central yolk-cells, which lie free in the cavity, and are not attached to its internal surface, gradually, and at length completely, disappear, They are not directly converted into the cells of the mucous membrane of the intestine. With regard to the first formation, and subsequent development of the intestinal system in Mammalia, the account given by Bischoff is in close ac- cordance with that furnished by Yon Baer* (See fig. 24.) The process pursued is very similar to that which takes place in the development of the intestine in the chick.] Digestive Glands.—The account given by Professor Muller]; of the mode of development of the large glands opening into the intestinal canal, as the liver and pancreas in birds, has been for the most part confirmed by Bischoff, in the case of Mammalia.^ The salivary glands also pursue a similar mode of development. || Development of the Respiratory Apparatus*^ Thymus Gland. — The development of the thymus gland has been investigated by Mr. Simon.** The earliest form in which he has dis- covered it, in the embryos of swine and oxen (on which animals his re- searches were, for the most part, made), is that of a simple tube, lying along the carotid vessels, and surrounded by faint indications of nascent areolar tissue. The contents of the tube are granular and dotted; its membrane is constituted of a fine, transparent, homogeneous tunic, pre- senting, at regular intervals, slight elongated thickenings of its substance, which are probably the remains of nuclei of primordial cells from the coalescence of a linear series of which it is most likely the tubule is originally formed. The second stage in the process of development is very analogous to the mode of growth attributed to true glands : the tube bulges at certain points of its length on one side or the other, and gives origin to diverticula or follicles, which maintain their connection with its cavity; and are filled with the same contents and bounded by the same transparent membrane as the tubule itself. Slight differences are observed in the mode in which these diverticula are formed, and in the rapidity with which the process takes place at different parts of the gland, but they ahvays tend to assume a more or less spherical form, and to retain their connexion with the main canal by means of a narrow isthmus of communication. In the further growth of the gland secondary and tertiary hollow projections extend from each of the primary follicles, and by a continuation of the process, new groups of follicles are successively * Muller’s Physiology, p. 1568, and fig. 208. f Ibid. p. 1540. J Physiology, vol. i. p. 489. § Op. cit. p. 322. || Page 323. H Midler’s Physiology, p. 1634. '** A Physiological Essay on the Thymus Gland. London, 1845, 4to.](https://iiif.wellcomecollection.org/image/b21967660_0123.jp2/full/800%2C/0/default.jpg)
