170 Mr John Goodsir on the Structure of the Intestinal 



selects and absorbs from the liquor sanguinis those parts of 

 the latter necessary for building up the peculiar tissue of 

 which the cell is the germ. It is in virtue of this peculiar force 

 that the secreting cell not only selects and absorbs, but also 

 in some instances elaborates, from the same common material, 

 the particular secretion of which it is the immediate organ. 

 And it is by the same force that the cell becomes the im- 

 mediate agent of absorption in certain morbid processes. 



The primitive cell, then, is primarily an organ of specific 

 absorption, and secondarily of nutrition, growth, and secre- 

 tion. 



With these few introductory observations on subjects which 

 T shall consider more at length on another occasion, I may 

 proceed to apply the laws of structure and function of the cell 

 to the structure and function of the intestinal villi. 



As the chyme begins to pass along the small intestine, an 

 increased quantity of blood circulates in the capillaries of the 

 gut. In consequence of this increased flow of blood, or from 

 some other cause with which I am not yet acquainted, the in- 

 ternal surface of the gut throws off its epithelium, which is 

 intermixed with the chyme in the cavity of the gut. The 

 cast off epithelium is of two kinds, — that which covers the vil- 

 li, and which, from the duty it performs, may be denominated 

 the protective epithelium, and that which lines the follicles, 

 and is endowed wath secreting functions. The same action, 

 4ihen, which, in removing the epithelia from the villi, prepares 

 the latter for their peculiar function of absorption, throws out 

 the secreting epithelia from the follicles, and thus conduces 

 towards the performance of the function of these follicles. 



The villi, being now turgid with blood, erected, and naked, 

 are covered or coated by the whitish-grey matter already de- 

 scribed. This matter consists of chyme which has undergone 

 the changes induced in it by the bile, of cast off epithelia of 

 the villi, and of the secreting epithelia of the follicles. The 

 function of the villi now commences. The minute vesicles 

 which are interspersed among the terminal loops of the lacteals 

 of the villus (fig. 6, PI. I.), increase in size by drawing materials 

 from the liquor sanguines, through the coats of the capillaries, 

 which ramify at this spot in great abundance. While this in- 

 crease in their capacity is in progi'ess, the growing vesicles 



