372 
Trypanosoma lewisi 
found in both parts of the intestinal tract, although sometimes one or 
the other is favoured with the greatest amount of pai’asites. 
The rosettes found in the pyloric region are no longer composed of 
large oval forms, but of round and small oval forms. Diagram XI, 
Fig. 2 shows a rosette of round forms without any external flagellum, 
dividing actively. The components of the rosette are united by a 
substance staining pink with Giemsa. 
Diagram XI. G. 
Figs. 1—3. Different forms of rosettes. 
Figs. 4—7. Bound forms. 
Figs. 8—9. Small oval forms. 
Figs. 10—12. Crithidiae. 
Figs. 13—17. Intermediate forms between crithidiae and small trypanosomes. 
Figs. 18—24. Small trypanosomes. 
This intercellular substance is often found in the rosettes. Prowazek 
referred to it when describing the forms from the louse. Sometimes 
this pink matter is absolutely structureless (in Giemsa and Heidenhain 
preparations). Perhaps in these cases it is to be considered as a 
product of the periplast. In other cases the substance has a distinct 
reticular structure, and then it seems to be composed of the more or 
