ORGANS OF THE BODY. 495 



either filling the whole apex of the villus in such myriads as to give it 

 the appearance of being diffusely infiltrated, or else ranging themselves in 

 long streaks, which may be mistaken for fine canals charged with fatty 

 globules, as they course along between the lymph cells and connective- 

 tissue fibres. In the third stage of the process we remark that the 

 minute fatty molecules have penetrated through the walls of the chyle 

 radical into its lumen, entirely filling the latter, so that this element of the 

 intestinal villus, at other times so difficult of detection, becomes dis- 

 tinctly visible, as has been already mentioned. The concluding phase of 

 the whole act is especially instructive ; here we see the columnar epithe- 

 lial cells and tissue of the mucous membrane again freed of fat, while the 

 chyle vessel is still full (fig. 476, p. 487). 



That this is the true course of the process may be confirmed by artificial 

 injection of the lymphatic canals in the mucous membrane of the small 

 intestine. 



The radicles of the chyle or lacteal system (fig. 489) are easily recog- 

 nised in the villi of the gut as blind canals, which in our opinion (in 

 which we are supported by Teichmann and His), are not continuous with 

 the actual tissue of the villus. According to the form of the latter, they 

 present themselves either single (a) or double (b), or even in greater 

 number (c). In the last case we either find a looped communication 

 between them in the apices of the villi, or the vessels end separately. 

 Towards the roots of the villi we not unfrequently encounter transverse 

 connecting branches. 



On arriving in the mucous membrane after leaving the villi, the lacteal 

 vessels descend through the former between the follicles of Lieb&rkuhn, 

 either directly or subsequent to the formation of a superficial horizontal 



CL-- 



Fig. 489. Vertical section of the human ileum. a, villas, with one chyle canal ; 6, another 

 with two; c, another with three; d, absorbent canals in the mucous membrane. 



network, which lies at the bases of the villi, and encircles with its meshes 

 the mouths of these glands of Lieberkuhn. 



At the boundary between the mucosa and submucosa, and in the 

 latter, a network (d) is formed by the intercommunication of these chyle 

 canals. These latter may be of considerable calibre, as in the sheep and 

 rabbit, or small, as in man and the calf. They accompany the network 

 of blood-vessels also here, and in some cases form sheaths around the 

 latter. As a whole, moreover, much variety is met with among them, 

 depending on the thickness of the mucous membrane and species of animal 

 chosen for observation. 



