16 ANATOMY OF THE LYMPHATIC SYSTEM. 



division, we are justified in saying that the fact of the cells being in 

 some parts of those patches more crowded, smaller, and less branched, 

 is due to a division of the branched cells, and that in this way such 

 a patch increases in breadth and thickness. 



From what has been said just now it is evident that the last 

 mentioned patches are, as regards their structure, similar to those 

 above mentioned, and that they are only further developed. 



As regards the spherical cells of different sizes previously men- 

 tioned, it can be stated : first, that they lie in the lymph-canal icular 

 system, as may be deduced from the negative silver-stained portions 

 of these patches ; secondly, that there exist all intermediate sizes 

 between where a rounded nucleus is surrounded only by a very 

 thin zone of protoplasm, up to cells which are twice as large as a 

 common colourless blood-corpuscle. From what has been said at the 

 commencement of this chapter we must claim also here, for at least 

 some of the lymphoid cells, that they are derived from the branched 

 cells of the matrix. 



Besides these patches, there exist in the omentum of rabbits a few 

 other structures, which, although under a lens they do not seem to 

 differ much from those previously mentioned, yet under a higher 

 power they exhibit between a network of capillary blood-vessels a 

 number of lymphoid corpuscles held together by a delicate reticulum 

 of branched corpuscles, similar to the reticulum of adenoid tissue. 



A last form, which is also very interesting, and which is not very 

 often to be foimd, is the following : from a tract which, besides a rich 

 system of blood-vessels, shows the same structure as the one just before 

 mentioned, or which tract contains only a larger artery and vein, a 

 small artery comes off, dissolves itself into a network of capillary 

 vessels, which join again into venous vessels, which return to the 

 previously mentioned tract. The matrix in which these capillaries 

 lie consists merely of a regular beautiful reticulum of nucleated- 

 branched cells, without having any visible intercellular substance. 

 Amongst the cells of the reticulum there are to be seen cells which 

 are apparently spindle-shaped. These are situated generally in a row, 

 accompanying the capillary vessels ; by lateral branches they seem to 

 join the branched cells of the reticulum. Looking at these apparently 



