160 JOHN STEPHENS LATTA 



same purpose? Is the function of the tonsils of the mouth and 

 intestine the same as that of the lymphatic nodes? These ques- 

 tions and others, in view of the evidence set forth in previous 

 investigation, make the intrepretation of the lymphatic tissue 

 difficult. 



HISTORICAL 



This confusion, regarding questions of lymphopoietic processes 

 is added to, in the study of the histogenesis of tonsillar tissue, 

 by the close relationship existing between the lymphatic tissue 

 of the tonsils and the overlying epithelium. This relationship 

 in fact, when the development of the tonsillar lymphatic tissue 

 first became a matter of investigation, led to the conclusion bj^ 

 some authors that the lymphocytes in these regions were of 

 epithelial origin. 



This belief was most vigorously defended by Retterer, who, 

 in a series of papers ('91, '92, '93, '09, '13) on the development of 

 the various tonsils, in each case declared the lymphocytes of 

 these structures were derived by downgrowths from the over- 

 lying epithelium. Von Davidoff ('86-'87), working on the for- 

 mation of lymphatic nodules in the jejunum of man and the 

 appendix of the guinea-pig, and Klaatsch ('92), studying the 

 histogenesis of Peyer's patch in the Echidna, are among those 

 who, like Retterer, thought the lymphocytes thus formed were 

 of epithelial origin. 



The majority of authors concerned with problems relative to 

 the histogenesis of tonsillar lymphatic tissue, however, disagreed 

 with these conclusions. Chief among these was Stohr, who, in 

 studying practically the same material as Retterer did, arrived 

 at very different conclusions He found the epithelium remain- 

 ing inactive in the formation of the tonsillar lymphatic tissue, the 

 elements of which were derived from the mesenchyme of the 

 tunica propria. Others agreeing with Stohr in ascribing to these 

 .cells in tonsillar structures a mesenchymal origin include Flesch 

 ('88), Zwarykin ('89), Tomarkin ('93), Kiickenmeister ('95), and, 

 more recently, Mollier ('13) and Hartman ('14). 



