496 



MANUAL OF HISTOLOGY. 



The arrangement of the lacteals is modified wherever Peyer's plaques 

 occur (fig. 490). Those lymphatic passages (), returning from the 

 modified villi of the circular ridges of these localities, form around 

 the tubular glands (b) of the villous ridges a network (#), which is 

 continuous with another system of intercommunicating passages (h) 

 formed in the reticular substance encircling the mesial zones of the 

 follicles. The latter open either into simple investing spaces enveloping 

 the basal portions of the follicles, and precisely similar to those of the 

 follicles in a lymph gland (in the rabbit, sheep, and calf for instance), or 

 (the case in man, the dog, and cat) these spaces are replaced by a system 

 of separate canals (i), interlacing around the bases of the follicles like 

 those we have already considered in 227. 



From this set of passages, or from the simple investing space, as the 

 case may be, the efferent lymph vessels finally take their rise. 



Returning now to the system of canals of the submucous tissue, we 



Fig. 490. 



find springing from it a certain number of regular knotted lymphatic 

 vessels, which empty themselves, after piercing the walls of the intestine, 

 into the subserous lymphatic trunks. These latter are arranged in a 

 narrow band following the mesenteric attachment of the gut (Auerbacli). 



The submucous lacteal network communicates, moreover, by means of 

 another set of passages with a second plexus of lymphatic vessels lying 

 between the longitudinal and transverse layers of muscle of the part. 

 This (fig. 488, p. 493), to which the name interlaminar network has been 

 given by Auerbach, accompanies the plexus myentericus situated here 

 also, with which we are already acquainted. It collects all the lymph 

 from the muscular substance of the intestinal tube, from a series of very 

 densely reticulated lymph canals of exceedingly small calibre, which are 

 found singly in the longitudinal tunic, but bedded one over the other in 

 the transverse layer. This interlaminar lymph net is connected finally 

 with the subserous trunks by efferent vessels. 



In this complex arrangement there is most undoubtedly a double pro- 



