26 ANATOMY OF THE LYMPHATIC SYSTEM. 



In that way one will be sure to find smaller or larger nodules, which 

 are in all stages of conversion into fat tissue. [From this it is also 

 evident that the fat tracts show here the same relations to the surface 

 endothelium as the perilymphangial nodules in general]. It is 

 remarkable that the distribution of the perilymphangial nodules 

 stands in an opposite relation to that of the fat tracts. The 

 more perilymphangial nodules and tracts an omentum contains the 

 smaller is the number of the fat tracts, and vice versa. In well-fed 

 half and full-grown dogs, and still more in cats and white rats, the 

 omentum shows only fat tracts and very few lymphangial nodules of 

 a very small size, in a state where the capillary system is just de- 

 veloping, whereas, in the omentum of rabbits, seldom, and then only 

 to a limited extent, fat tracts appear. > In the omentum of guinea- 

 pigs and that of the monkey the lymphangial nodules and fat tracts 

 are pretty equal, even in the most favourable conditions. In the 

 pleura mediastini there is a very much smaller tendency for the 

 lymphangial nodules to become converted into fat tracts, whereas in 

 the mesentery, even of the rabbit, the tendency is great; from 

 which it is evident that the conversion of lymphangial nodules into 

 fat tissue does not take place equally in all serous membranes, nor in 

 all animals the mesentery has the greatest, the pleura mediastini 

 the smallest tendency. In cats, dogs, and rats there is a much 

 greater tendency than in guinea-pigs or monkeys, and the smallest is 

 to be found in rabbits. 



There are two other points with regard to the fat tracts still to be 

 mentioned, namely : 1 . That as long as a lymphangial nodule does not 

 become converted into a fat nodule there are always, as we have 

 seen, numerous lymphoid cells to be found in it, which, as we have 

 pointed out, are at least partly to be considered as offsprings of the 

 branched cells of the stroma of the nodule. But as soon as a lym- 

 phangial nodule becomes converted into a fat nodule the lymphoid 

 cells become fewer, or, at any rate, are not to be found in the same 

 number as before. We must therefore conclude that the surplus of 

 nourishment which the cells of the matrix are provided with is all 

 consumed in the production of the fat, whereas, previously, it had 

 been employed for the production of lymph-corpuscles. After what 



