222 THE AMEBIC AX XATURALIST [Vol. LI 



without difficulty and although the sporulating forms, 

 characterized by the presence of the daughter nuclei, are 

 also observable, both of these are relatively uncommon, 

 and the stage which shows the well rounded ball of re- 

 serve-substance C'Reservestoffsballen") is seldom met 

 with. How can these phenomena be explained? 



The writer has introduced this point in connection with 

 the discussion of the methods of nutrition of the flagel- 

 lates, simply because it seems possible that the morpho- 

 logical differences alluded to above are conditioned by 

 the nature of the food supply. The writer has already 

 traced the changes which the food vacuole of TricJiomonas 

 undergoes during the process of encystment. It was 

 shown that there is a direct transformation from the food 

 vacuole of the trophozoite, laden with bacteria and cocci, 

 to the ball of reserve-substance which eventually crowds 

 out the nucleus, chromatic line and line of blocks from the 

 inner part of the cell and may possibly absorb the axo- 

 S'tyle. Finally it comes to lie as a mass of varying size 

 with respect to the cell, in the center, or slightly to the 

 ventral side of the organism. Its staining qualities sug- 

 gest a glycogen-like substance, and its density appears to 

 vary with the stage of digestion of the food substances 

 which are to serve the young daughter cells. 



As stated above, this well defined reserve-substance 

 mass is seldom observed, at least well developed, in the 

 flagellates located deep in the tissues where the evidence 

 favors a view of nutrition by osmosis. The question is 

 therefore raised : Can it not be that the marked difference 

 between the appearance of the flagellates in the tissues 

 and in the cecal content is dependent directly upon the 

 nature of the store of reserve food; and thus indirectly 

 upon the manner of nutrition. This view is in agreement 

 with the general observation that protozoa that subsist by 

 osmosis seldom manifest either food vacuoles or definitely 

 segregated bodies of reserve food substance. 



In just what way the presence or absence of a ball of 

 reserve-substance would explain all the differences ob- 

 served in the parasites in and out of the tissues it is diffi- 



