229] STUDIES ON GREGARINES— WATSON 19 



sorption takes place through the epimerite, as the cephalont develops 

 there occurs a gradual change in food from the predigested cell sap to the 

 juices free in the intestinal tract as well as a transfer in its mode of ab- 

 sorbing these substances from the epimerite to the general epicyte of the 

 body. The general epicyte of the body may be physiologically different 

 when the cephalont is very young from that when it is nearly ready to 

 discard the epimerite. 



The third question : Does the epicyte of the gregarine body absorb 

 all the food from the lumen of the intestine and the epimerite only act as 

 a holdfast f has been answered above in the negative. There may come a 

 time when maturity approaches and the epimerite is at the point of being 

 discarded when the question may be answered in the affirmative ; during 

 the greater part of the cephalont life, however, the epicyte is probably 

 ineffective in absorbing nourishment. 



75 a toxic substance given out into the parasitized cell through the 

 epimerite of the parasite? Siedlecki (1901 :100) says the presence of the 

 parasite within the cell (Monocystis ascidiae) incites hypertrophy, then 

 atrophy, and that these phenomena are due to the chemical action of the 

 parasite. In another species, however, Nina gracilis, which possesses nu- 

 merous long protoplasmic filaments which penetrate deeply into the epi- 

 thelium of the intestine, the author says of these threads 



"Tous ces changements provoques dans repithelium sont de nature pure- 

 ment mechanique." 

 He has observed changes in form and displacement of the cells but re- 

 gards these as unallied to the hypertrophy and atrophy which is induced 

 by chemical excitation. 



Siedlecki finds in one instance a chemical effect excited by the pres- 

 ence of the parasite in or attached to a cell ; in another species purely a 

 mechanical affect ; while Leger and Duboscq, as mentioned, believe the ap- 

 parent hypertrophy due to mechanical irritation of the parasite upon the 

 cell rather than to any toxin secreted by the parasite. Yet illustrations 

 given by Leger and Duboscq to prove a mechanical effect indicate a dif- 

 ferent staining reaction in the case of many of the parasitized cells and 

 a rearrangement of the chromatin in the nucleus unlike that in normal 

 cells. 



The last question is stated as follows : Is a toxic substance given out 

 through the epicyte of the parasite into the lumen which is absorbed by 

 the parts of the epithelium nearest the surface? It is often the case that 

 the free end of the cell is shrivelled first. This end is nearest the hypo- 

 thetical center of influence of the toxin which would be given out through 

 the body of the parasite exposed in the lumen. It is also the end which 

 is penetrated by the epimerite and the part naturally used as food first. 

 The fact that the whole ceU often reacts differently to the stain and not 



