THE (ENOCYTES OF PLATYPHYLAX DESIGXATUS 



WALKER. 



WILSON P. GEE. 



INTRODUCTION. 



The oenocytes as unique cells of the body of all of the orders 

 of insects which have been investigated, except the Aptera, have 

 received much attention within the last couple of decades, but 

 with relatively little more than mere conjecture as to their defi- 

 nite function. \Yith the idea of throwing added light on the 

 nature of the activities of these cells, the investigations here dis- 

 cussed were made on the larvae, pupae, and adults of Platyphy- 

 Id.v desif.'jnttiis, a caddis-fly, which occurs quite abundantly in 

 fresh-water springs in the vicinity of Madison, Wis. 



The results here presen;ed were derived from a study of the 

 structure of the cenocytes in several periods of the life-history 

 of this insect, and by injection experiments. Several stains 

 \\ere tried, Heidenhain's iron-haematoxylin proving the best for 

 detailed work. Delafield's haematoxylin wrh orange G or eosin 

 \\ere the stains used in determining the location and number of 

 the cenocytes. The cytoplasm of the oenocytes takes up eosin 

 very readily, as it does also orange G. The substances used in 

 injections were methylene blue as an intra-vitam stain and 

 sulphindigotate of sodium to test the excretory nature of the 

 cells. 



The papers of Perez (1903), Rossig (1904), and \\Vi-senberg 

 (1907), presenting a rather complete review of the work done on 

 cenocytes, it will here be necessary only to briefly mention some 

 of the chief contributors to the subject. 



According to Ro^ig (1904), the lux to observe tin- u-nocytes 

 special organs was M. Kabrc (1856). 



Landois (1865) distinguished them from the fat-bodv, and 

 gave to them the name " Respirationszellen " 1> icause of the rela- 

 tion he obser\ed them to bear to the tracheae. 



