252 The Philippine Journal of Science ms 



membranes. Using Trypanosoma gambiense, he was able to 

 secure infections per os, care being taken to prevent the pos- 

 sibility of producing lesions in the mouths of the rats used. 

 Attempts to secure infection by coitus between rats were un- 

 successful, but careful experiments in infection through the 

 vagina were successful. Infection was also secured by applying 

 the infected blood to the unshaved skin of rats, and Hindle con- 

 cludes that Trypanosoma gambiense is able to penetrate the 

 sound mucous membrane and the undamaged skin. 



It seems from this that certain, at least, of the flagellates 

 experience no difficulty whatever in penetrating cells and tissues. 

 Minchin and Thomson have shown that apparently the side of 

 the cell is the most vulnerable point. Furthermore they cite 

 the adhesive properties of the flagellum under certain circum- 

 stances when the organism may attach itself to the epithelial 

 surface by its flagellum and then bore its way in, posterior end 

 first. Might not a similar action be possible in the case of 

 Trichomonas, where the axostyle would play an important part? 

 This, of course, apart from the condition where Trichomonas 

 might assume an amoeboid form, as described by Castellani(V) 

 for Entamoeba undulans, and bore its way in by its long, powerful 

 pseudopodium. Crithidia is known to attach itself to epithelium 

 by its shortened flagellum. This would give us, then, three 

 separate relations existing between intestinal flagellates and the 

 epithelium : 



1. Close application to the surface of the epithelium without 

 actual penetration. Lamblia. 



2. Attachment by a flagellum, which may penetrate the cell 

 membrane. Crithidia. 



3. Actual penetration of the cell and entrance of the entire 

 organism into the cell body and subsequent liquefaction of the 

 cell contents. Trypanosoma, Trichomonas, Hexamitus, and pos- 

 sibly Lamblia. 



The amoeboid, flagellated, and ciliated protozoa of the ali- 

 mentary tract represent a group standing apart from the other 

 protozoan parasites. For the most part they are, in regard 

 to structure, mode of life, and nutrition, not very different from 

 free-living forms we may find in almost any mud puddle or 

 watering trough. That they show certain tendencies toward 

 development to obligatory tissue parasitism cannot be denied, 

 but they can scarcely be said to have "arrived." 



The amoeboid forms as represented by the entamoeba? are 

 strikingly similar in structure and mode of life to Vahlkampfia 



