20 ANATOMY OF THE LYMPHATIC SYSTEM. 



are justified in concluding that the lymphoid corpuscles which are to 

 be found in the spaces of the reticulum are offsprings of the cells of 

 that reticulum. 



If we examine one of the above-mentioned membranes without 

 special preparation we often find nodules and tracts marked only as 

 an accumulation of lymphoid corpuscles. After what we have stated 

 in the foregoing pages it would be perfectly erroneous to say that the 

 nodules and tracts of the omentum represent only accumulations of 

 lymphoid corpuscles (KnaufT, Kecklinghausen) ; and it would be not 

 less incorrect to say that they resemble follicular tracts of lym- 

 phatic glands, viz. consist of adenoid tissue (Sanderson). We have 

 seen, namely, that there exist several marked varieties in the nodules : 



a. Simple accumulations of germinating endothelium of the surface ; 



b. Accumulation of more or less flat branched cells, or what comes to 

 the same, accumulation of lymph-canalicular systems, the lacunae of 

 which become by the gradual division of their cells nearer to each 

 other, and become provided in this way with less numerous and 

 shorter canaliculi. Further, we have seen : c. Nodules which per- 

 fectly resemble adenoid tissue ; and finally, (d) we have found vascu- 

 larised nodules, the matrix of which consists of a reticulum of large 

 more or less flat branched cells, the spaces of which are generally 

 occupied by fluid, or by a very limited number of lymphoid corpuscles ; 

 that is to say, the matrix is replaced by a space filled with fluid, 

 which space is subdivided into a number of small spaces by a reticulum 

 of branched cells. 



As we shall see in the chapter on the lymphatic vessels, the varieties 

 c and d form one category of nodules and tracts, which, as they develop 

 in lymphatic vessels, may be called endolymphangial nodules and 

 tracts, whereas the nodules included in variety b lie outside lym- 

 phatic vessels, but in close connection with their wall, and may there- 

 fore be called perilymphangial nodules and tracts. 



We must, however, add that we do not intend to draw a hard line 

 as regards structure between c and d on the one hand and b on the 

 other hand, at least not for the guinea-pig, cat, dog, or monkey ; for 

 we have not unfrequently seen nodules and tracts, the peripheral parts 

 of which consisted of large more or less flat branched cells, which 



