MINUTE ANATOMY OF THE ALIMENTARY CANAL. 215 



of branched cells of the retiform tissue, but of a reticulum 

 which does not differ from that which is found in the lymphoid 

 follicles, consisting of a network of fibres with thickened 

 nodes. The reticulum contains cells in its meshes. These 

 cells are of two kinds, lymph-corpuscles and large, somewhat 

 flattened, spheroidal cells arranged as an endothelium (see 

 figs. 1 and 3) ; they are very similar to the endothelium of 

 the blood-vessels, lymphatics, and membrana propria. The 

 lymph-corpuscles are found chiefly at the lower part of the 

 villi and the spheroidal cells at the upper part. It is, how- 

 ever, distinctly stated that a gradual transition can be traced 

 from the lymph-corpuscles to the endothelial-like cells of the 

 upper parts of the villi. In the mucosa no fibrous tisue can 

 be found, as has been figured by some authors. 



The mode in which the muscles terminate in the rabbit's 

 colon and in the villi of many animals (see m, fig. 1) is 

 described. It is found that the bundles of muscles separate 

 into individual fibres, which, running up to the surface, are 

 apparently attached to the cells of the membrana propria. 

 It is demonstrated, however, by oblique and cross sections of 

 the muscularis mucosae, that every muscle fibre is surrounded 

 by the reticulum, and that this reticulum is continuous with 

 that of the rest of the mucosa. It is by this reticulum that 

 the muscle bauds running up towards the surface are attached 

 to the cells forming the membrana, or, more correctly, to the 

 reticulum surrounding the cells forming the membrana. 



It is shown that in some animals the chyle-vessel is at 

 least half surrounded by a membrane of muscle-fibres dove- 

 tailing into one another. The importance of this fact 

 appears to be that any theory which attempts to prove the 

 absorption of fat by means of branched connective- tissue- 

 corpuscles connected to the chyle-vessels, &c., must, in such 

 a case, be evidently at fault ; and if it were not for the know- 

 ledge of the delicate reticulum pervading and holding in its 

 meshes all the other tissues of the villus including the 

 muscle-fibres, this one fact would make great difficulty in the 

 comprehension of the process of fat absorption, unless we fol- 

 lowed Frerichs, Donders, Funke, and Donitz, in supposing 

 that the fat presses in everywhere in a cloud-like form. 



The blood- and chyle-vessels are shown to be composed of 

 a membrane formed of endothelial plates, a delicate reti- 

 culum being found between the individual endothelial cells 

 (see r, fig. 2), this reticulum being continuous with that of 

 the rest of the mucosa, and forming the adventitia to the 

 vessels. There is a difference between the adventitia of the 

 arteries and veins, so that we may always recognise the 



