OF THE INTESTINAL VILLL 9 



other cause with which I am not yet acquainted, the internal 

 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 villi, and which, from the 

 duty it performs, may be named protective epithelium, and that 

 which lines the follicles, and is endowed with secreting functions. 

 The same action, then, which, in removing the protective epi- 

 thelia from the villi, prepares the latter for then- 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 described. 

 This matter consists of chyme, 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 inter- 

 spersed among the terminal loops of the lacteals of the villus, in- 

 crease in size by drawing materials from the blood through 

 the coats of the capillary vessels, which ramify at this spot in 

 great abundance. While this increase in their capacity is in 

 progress, the growing vesicles are continually exerting their ab- 

 sorbing function, and draw into their cavities that portion of the 

 chyme in the gut necessary to supply materials for the chyle. 

 When the vesicles respectively attain in succession their specific 

 size, they burst or dissolve, their contents being cast into the 

 texture of the villus, as in the case of any other species of inter- 

 stitial cell. 



The debris, and the contents of the dissolved chyle cells, as 

 well as the other matters which have already subserved the nu- 

 trition of the villus, pass into the looped network of lacteals, 

 which, like other lymphatics, are continually employed in this 

 peculiar function. As loiig as the cavity of the gut contains 

 chyme, the vesicles of the terminal extremity of the villi continue 

 to develope, to absorb chyle, and to burst, and their remains and 

 contents to be removed along the lacteals. 



When the gut contains no more chyme, the flow of blood to 

 the mucous membrane diminishes, the developement of new 



