CELLULAR ELEMENTS OF THE GROUND-SUBSTANCE. 27 



has been said above about the transformation of the branched cells 

 of the stroma into fat cells, it is unnecessary for me to warn the 

 reader against the possible assumption that in the transformation of 

 lymphangial nodules into fat nodules the lymph-corpuscles are the 

 elements which become converted into fat-cells according to the 

 previous assertions of histologists and consequently we could easily 

 understand why the number of these lymph-corpuscles decreases as 

 this transformation is going on. For in contradiction to such as- 

 sertions we have the above stated fact that the fat cells are trans- 

 formed branched cells of the stroma of the nodule. Besides, the 

 decrease of the lymph-corpuscles can easily be explained in another 

 way. We have seen that the -branched cells of the stroma of the 

 nodule lie in the corresponding lymph-canalicular system, together 

 with the lymph-corpuscles. Under ordinary circumstances, one must 

 suppose that the lymphoid corpuscles, after they have detached, viz. 

 constricted, themselves from those branched cells, are carried away 

 into the lymphatic vessels, into which, as we shall see afterwards, 

 that lymph-canalicular system leads. As soon as the branched cells 

 of the matrix become converted into fat cells the production of new 

 lymph-corpuscles is diminished to a very great extent, and, conse- 

 quently, there is very little here that can be carried away. 



2. The second point we wish to call attention to is the fol- 

 lowing : the lymphangial nodules and tracts grow relatively quicker 

 when they are going to become converted into fat tracts. That is seen 

 best in the mesentery. Here, for example, in cats and in rabbits it is 

 very easy to find that the number and size of lymphangial nodules 

 and cords increases very much in the neighbourhood of fat tracts. 



It is plain, therefore, after all we have said about the fat tracts, 

 that we are in agreement with Fleming in saying that fat cells are 

 transformed branched cells, but that we are not in agreement with 

 that observer in saying that fat tissue develops in the adventitia of 

 arteries. What we have already pointed out is that the formation 

 and growth of the lymphangial nodules is generally, not always 

 though, closely related to the larger blood-vessels, and we shall see 

 in one of the following chapters that the development of the lymph- 

 angial nodules, and consequently also that of the fat nodules and fat 



