THE GENUS TRYPANOSOMA 



249 



criticism that no sexual phases have as yet been found in the blood of 

 vertebrates is not wholly unanswerable, since we do not yet know 



FIG. 100 



Trypanosoma raia. (After Robertson.) Forms observed in the digestive tract of the leech, 

 Pontobdella muricata. ^1, mature specimen from blood of skate; B to F, stages in the 

 development of the flagellum from the kinetonucleus, and change in position of the latter in 

 relation to the nucleus. 



much about the conjugation processes in any species, while Hintze's 

 view is conceivable, viz., that the organisms migrate from the blood 

 back into the intestine, where they conjugate, while in blood-sucking 



