480 J. A. BADERTSCHER 



source of the eosinophile cells in the interlobular septa of the 

 thymus of the pig is the same as that of the granular cells of 

 Watney, the only difference is that he derived them directly 

 from connective tissue cells while in the pig thymus they are 

 derived from transformed connective tissue cells, the large 

 lymphocytes. 



Of course, in fixed material it is difficult to determine whether 

 all the lymphocytes along the blood vessels are derived from 

 the loose connective tissue in which the vessels lie or whether 

 some come from the blood. Two features are in favor of the 

 former view; (1) transition forms from connective tissue cells to 

 lymphocytes are of frequent occurrence. The lymphocytes 

 thus formed through division also increase in number; (2) 

 diapedesis of the leucocytes is thought of as taking place only 

 through thin walled blood vessels, but the lymphocytes and 

 eosinophile cells are as numerous along the course of thick 

 walled vessels as along those of a capillary nature. Another 

 possible source of the lymphocytes in the septa is from the par- 

 enchyma of the thymus. However, in late stages that por- 

 tion of the thymus contains mostly small lymphocytes and 

 judging from the small number of small lymphocytes present 

 in the septa very few have migrated into them from the par- 

 enchyma. Only a few eosinophile cells were found undergoing 

 mitosis, so the number of this type of cells formed through their 

 proliferation is almost neglible. 



The source and nature of all the granules in eosinophile cells 

 is difficult to determine. There is, however, no evidence indi- 

 cating that the granules are debris of degenerated epithelial 

 cells, as held by Schaffer ('09), but ample evidence that 

 not all are products of the protoplasmic activities of the cells 

 containing them, which view is held by Maximow for the ori- 

 gin of the granules of the myelocytes found in the thymus of 

 various animals. Mention was made of free eosinophile gran- 

 ules (fig.. 8, Eo.G.) in the interlobular septa where free red blood- 

 cells also occur. These can be traced directly to degenerated 

 red blood-cells, but the free granules usually observed in the 

 septa of any developmental stage do not seem to be numerous 



