492 



MANUAL OF HISTOLOGY. 



between adjacdftt investing spaces, which are lost at the level of the 



mesial zone. 



In other plaques, instead of these continuous investing spaces, the 



surface of the base is covered by numerous fine lymphatic canals, like a 



child's toy ball with a net. 

 In the connecting layer, 

 between th& mesial zones, a 

 network of similar passages 

 may likewise be recog- 

 nised. 



The walls of these pas- 

 sages, then, are made up of 

 very small -meshed lym- 

 phoid reticular substance. 



In the actual follicles 

 themselves, however, no 

 such passages exist. 



We have only to add, that 

 the superficial lymphatic 

 canals of the mucous mem- 

 brane, of the smooth as 

 well as villous annular 

 ridges, all sink down to 

 empty themselves into these 

 lymph passages of the con- 

 necting layer already men- 



Fig. 486. Transverse section through the equatorial plane of 

 three of Peyer's follicles from the rabbit, a, capillary net- 

 work ; 6, large circular vessels. 



tioned ; also that, at least, 



a part of the investing 

 spaces around the follicles 

 is clothed with the characteristic vascular epithelium of the lymphatic 

 system (p. 377). 



The vascular supply of each follicle is composed (as was demonstrated 

 many years ago by myself) of an exceedingly complex network of delicate 

 capillaries, from about 0*0056 to 0'0074 mm. in diameter. This network 

 (fig. 485, a) stands in close connection with the large arterial and venous 

 vessels (&), which course up and down between the follicles supplying the 

 villi (e) of the intestine, as may be seen in vertical sections. In trans- 

 verse sections the arrangement of the capillaries in the interior of the 

 follicles is seen to be in lines converging towards the centre (a), starting 

 from circular vessels externally an object of extreme beauty under the 

 microscope. 



257. 



The nervous apparatus of the small intestine is exceedingly compli- 

 cated, deriving its roots from the ventral divisions of the vagus and 

 sympathetic. It consists of a double plexus of microscopic ganglia con- 

 nected above with the nerves interlacing in the walls of the stomach. 



In the submucosa we first meet with the plexus 1 of Remalt and Meissner, 

 remarkable for its highly developed knots. Prom this pale nucleated 

 fibres are given off, principally to the muscularis of the mucous mem- 

 brane, and muscular bundles in the villi, and to a minor extent to the 

 surface of the membrane as sensory elements. We are still lacking in 

 observations on these points, however. 



