ABSORPTION FROM THE DIGESTIVE CAVITY. 



441 



461. When the Villi are examined at such a period after a meal containing 

 oleaginous matters, as has sufficed for its partial digestion, their lacteals are 

 seen to be turgid with chyle (Fig. 134, A) ; and the extremity of each lacteal 



Fig. 134. 



Fig. 135. 



Extremity of Intestinal ViHus: seen at A, during absofption, and showing absorbent cells and lacteal trunks, 

 distended with chyle; at B, during interval of digestion, showing the supposed peripheral network of lacteals. 



appears to be imbedded in a collection of globules presenting an opalescent ap- 

 pearance, which gives to the end of the villus a somewhat mulberry-like form. 

 It was supposed by Prof. Goodsir, 1 by whom this appearance was first observed, 

 that these globules are cells developed within the basement-membrane, during 

 the act of absorption, from what he considered to be granular germs visible in 

 the same situation during the intervals of the process (B); and that these cells, 

 drawing into themselves during their growth certain 

 of the nutritive materials contained in the intestinal 

 canal, are thus the real agents in the selection of the 

 substances which are to be introduced into the lac- 

 teals, delivering them to these, by the rupture or 

 deliquescence of their walls, so soon as their own 

 term of life is ended. It was further held by Prof. 

 Goodsir, that the epithelium-cells covering the ex- 

 tremities of the villi fall off during the process of 

 absorption, so as to leave the villi more free to im- 

 bibe the fluids in contact with their surface ; and 

 thus that a new set of absorbent cells is developed 

 with every recurrence of the act of absorption, and 

 a new set of protective epithelium-cells in the sub- 

 sequent interval. These views, however, though 

 correctly indicating the fact that the elements of 

 chyle are introduced into the lacteals by the inter- 

 mediation of cells, have been shown to be erroneous 

 so far as regards the nature of these cells ; which 

 several excellent observers 3 agree in regarding as 

 the proper epithelium-cells of the villi these not 



being thrown Off, as Prof. Goodsir believed, but SO during absorption: a, marginal layer 



completely changing their aspect in consequence of of e P ithelium -eUs: z>, epithelium- 



the imbibition of oleaginous flnid (Fig. 135), that 



they cease to be recognizable as such, unless their 



intermediate stages be traced. The epithelium-cells of the villi may frequently 



be observed (as formerly mentioned) to be connected at their free extremities 



_ "Edinb. New Phil. Journ.," July, 1842; and "Anatomical and Pathological Observa- 

 tions," pp. 5 10. 



2 See MM. Gruby and Delafond, in "Comptes Rendus," 5 Juin, 1843; Kiiss, in "Gaz. 

 Med. de Strasbourg," No. 2, 1846; E. H. Weber, in "Miiller's Archiv.," 1847; Kolliker, 

 " Mikroskopische Anatomic," bandii. 169; and Bennett, in "Edinb. Monthly Journal " 

 March, 1852, p. 283. 



Extremity of an Intestinal Villus 



