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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![support to our future inquiries into the mechanical metamorphosis of matter, for there exist innumerable relations by which the result of such calculations may be completely modified. It would carry us too far from our subject were we to enumerate all these relations ; we will, therefore, simply remark that probably a large quantity of fat is not conveyed from the chyme to the lacteals, but is resorbed by the veins, for how otherwise could the portal blood of animals be almost twice as rich in fat during the process of digestion as in the fasting condition ? (See p. 619 of the first volume.) We cannot entertain any doubt as to the origin of the chyle, since nature itself has clearly manifested its source to us. Certain questions here present themselves as to the mode in which the individual consti- tuents pass into the lacteals, and the alterations which they undergo within these vessels. The lacteals originate in the axis of the villi which are spread over the whole of the small intestine, and present small club- like dilatations. The lacteals are surrounded at their origins by vesicles or cells which appear as if imbedded in an indistinct fibrous mass ; while nearer to the exterior and to the peripheral investment of cylindrical epithelium covering the intestinal villi, there lie the trunks of the minute bloodvessels, which communicate together by means of a very fine net- work of capillaries. According to E. H. Weber,1 there is a layer of round cells situated immediately below the epithelium, which are col- lapsed during fasting, and inflated like well-filled vesicles during the process of digestion. All observers concur in the opinion that each in- dividual particle of cylindrical epithelium participates in the process of resorption, and is filled with a granular substance which causes its distension, and in some cases even a slight distortion. It is, however, more especially and almost exclusively during digestion that this layer of round cells appears under the epithelial investment ; some of these cells being then filled with a clear, transparent, faintly yellow fluid, others with a granular substance. Thus we often find a cell of this kind filled with limpid fluid situated on the apex of an intestinal villus, and close by it another cell of equal size, filled with granular emulsive matter. Besides numerous observations on animals in relation to this point, I remember noticing this appearance most strikingly and distinctly in the intestinal villi of a decapitated criminal, in whose examination E. II. Weber had permitted me to take part. The microscopical preparations made by Weber at the time have kept so well, that they still fully testify to the accuracy of his observations, and show that the structures in question are neither epithelial cells filled with fat (as was conjectured by Frerichs) nor fat-globules merely adhering to the surface of the villi. The distortion of the cells which Frerichs was also unable to detect, may likewise be easily recognized in these preparations. The limpid contents of these clear globules, which are probably the oscula of the intestinal villi, according to the views of the older physio- logists, can from their refractive power scarcely be anything but fat, 1 Miiller's Arch. 1847, S. 399. [We may also refer the reader to Professor Goodsir's remarks on this subject in his Anatomical and Pathological Observations, pp. 5-10. —G. E. D.]](https://iiif.wellcomecollection.org/image/b21136300_0023.jp2/full/800%2C/0/default.jpg)
