* 



BEHAVIOR OF ANURA TOWARD COLLOIDAL DYES 3 



the most part derived from embryonic mesenchyme and meso- 

 thelium. Cells derived from embryonic entoderm and ectoderm 

 have also been observed to react toward these dyes. 



The derivatives of mesenchyme which react toward the dye are 

 largely confined to the vascular system. They include its venous 

 and lymphatic endothelium to a greater or less degree and some, 

 at least, and possibly all of the so-called white blood-corpuscles. 

 Apart from the vascular system the derivatives of mesenchyme 

 which have been observed to react toward the dye include cells 

 of the reticulum in certain organs, fibroblasts, the interstitial cells 

 of the testis, granulosa cells of the atretic follicle (Evans, '1C) 

 connective tissue cells and giant cells of the placenta. 



By far the most important cells of mesothelial origin which 

 react toward acid dyes are the epithelial cells of the renal tubules. 

 Cells of mesothelial origin which have also been observed to 

 react toward the dye are those which line the walls of the coelomic 

 cavity and cells of the epicardium and adrenal bodies. 



The ectodermal cells of the placenta have been observed to 

 react toward the dye ; also cells of entodermal origin, as the epi- 

 thelium of the pharynx (anura), hepatic cells and cells of the 

 epithelial bodies. 



Although it is evident that the storage of colloidal acid dye 

 particles is not accomplished in all of the above-mentioned cases 

 by a process of phagocytosis, the circumstance that the reac- 

 tions toward acid dyes are limited and confined exclusively to the 

 cells of certain typical tissues appears to be a question of consider- 

 able significance. What these reactions may consist of in 

 individual cases is not especially concerned in the present 

 investigation. 



Wilsocki ('16, '16a) has recently observed when young frog 

 larvae are placed in a solution of colloidal acid dye, as trypan 

 blue, that the latter gains admission to the body and certain 

 tissues, including lymphatic endothelium, then react toward the 

 dye in a typical and characteristic manner. The circumstance 

 that dye gets into the circulation in some manner and so elimi- 

 nates the necessity of injecting it into such young larvae, has 

 somewhat broadened the possibilities of the field of inquiry. It 



