THE HISTOGENESIS OF DENSE LYMPHATIC TISSUE 183 



in the midst of the nodules. They are usually found in quite 

 intimate association with the blood vessels of the mucosa. In 

 the appendix they are found in greater abundance than in the 

 iliac tonsil of the same individual. 



Modern hematologists are practically united in declaring for 

 eosinophile leucocytes (granulocytes) an origin, either directly 

 or indirectly, from cells of a lymphoid character. But, in respect 

 to eosinophile cells of the intestinal mucosa, it must yet be 

 decided whether they arise by local differentiation of lymphoid 

 cells or have been carried in and dropped there by the blood 

 stream. 



Hartmann ('14) observed the large groups of granulocytes 

 in the region of the intestinal tonsils, and he considered the ma- 

 jority of them to be true eosinophile leucocytes, with somewhat 

 rodded granules, and a polymorphous nucleus. He found, 

 rarely, mononuclear forms with a light staining nucleus. He 

 considered the eosinophils found here as having been carried in 

 by 'the blood stream. 



Weill ('19), on the other hand, in studying the formation of 

 the eosinophiles of the intestinal mucosa, favored the view that 

 they were differentiated in situ from cells of a lymphoid charac- 

 ter (lymphoid hemoblasts). He found transitional stages be- 

 tween the non-granular lymphocytes, through mononuclear 

 granular forms, the ' eosinophilic myelocytes, ' to a polymorpho- 

 nuclear eosinophilic leucocyte. He declared that the young 

 mononuclear forms, at least, could not have been carried in by 

 the blood stream, for no cells of that type were found in the blood, 

 all there being of the polynuclear or polymorphonuclear type. 



Although hematologists are practically agreed as to the lym- 

 phoid origin of granulocytes, the question of the origin and sig- 

 nificance of the acidophihc granules of the eosinophiles is still 

 a much debated one. Several authors are of the opinion that 

 eosinophiles are derived from neutrophils or other special cells 

 by change in the granular character (van der Stricht, Gulland, 

 Thayer, Arnold, Jolly, et al.). Others considered that neutro- 

 phils might transform into eosinophiles after taking up exoge- 



