234 JAMES ERNEST KINDRED. 



thought that digestive substances were carried from the rete 

 mirabile peritoneum in the Holothuroidea to the stomach epithe- 

 lium by " amcebocytes. " Thus there are several conceptions 

 concerning the relations of the leucocytes to the digestive activi- 

 ties which need further investigation. 



As evidenced by their tendency to remove foreign particles 

 from the body cavity the leucocytes may be regarded as excretory 

 agents and further observations as to their excretory activities 

 should be considered. Durham ('88) and Chapeaux ('93) 

 observed that the phagocytic cells leave the body through the 

 papulae in the Asteroidea. I have observed such a migration in 

 Leptasterias hexactis, in which, after injection with carmine, the 

 papulae are reddish and a smear from the outer surface reveals a 

 number of leucocytes laden with carmine particles. "Amcebo- 

 cytes" (particular type not stated) have been observed to leave 

 the body cavity of the Holothuroidea by diapedesis through the 

 walls of the branchial tree into its lumen and thence to the out- 

 side (Herouard, '95; Schultz, '95). Therefore, there is evidence 

 that the exit of the phagocytes in the Echinoderms is through 

 the body wall. 



The exact relation of the leucocytes in the removal of waste 

 substances from the tissues has not been proven, but Delage and 

 Herouard ('03) thought that substances absorbed from the tissues 

 by "amcebocytes" are reprecipitated in them in the form of 

 granules and may possibly give rise to the various "amcebocytes 

 with spherules." List ('97) pointed out earlier that substances 

 absorbed by the "amcebocytes" may be the cause of the develop- 

 ment of a crystalloid in the nucleus of cells of this type, which by 

 growth causes a degeneration and finally the destruction of the 

 cell. Thus the accumulations of crystalloids observed scattered 

 throughout the body of various Echinoderms may be regarded 

 as the remnants of degenerate excretory "amcebocytes." 



Another activity of the active leucocytes is the formation of 

 plasmodial masses which are very numerous in any drop of peri- 

 visceral fluid. That these plasmodia are formed by the fusion of 

 active leycocytes has Uvn <>l>~cr\ <<! frequently and plasmodial 

 formation is one of the activities which distinguishes the active 

 from the passive phase of the leucocyte and from other cells in the 

 perivisceral fluid. 



