TRYPANOSOMA CRUZI 



491 



about 4 microns in diameter. This commences to divide by simple fission 

 after division of its nucleus and kinetoplast (Fig. 207, 17-20). By repeated 

 fissions in this manner intracellular cysts are produced which contain large 

 numbers of leishmania forms. The cyst is more of the nature of a vacuole, 

 as a definite wall is not present, the cell being enlarged and reduced to a 



Fig. 207. — Trypanosoma cruzi in Smear of Heart of a Mouse (x 2,000). 

 (Original from Preparation made by Dr. Tejera.) 



1-9. Stages in development of a trypanosome from rounded flagellated stage. 

 10-15. Stages in development of a trypanosome from elongate flagellated stage. 



16. Posterior nuclear trypanosome form. 17-20. Division of leishmania form. 



21-23. Growth of flagellum in leishmania form. 24-28. Division of flagellated forms. 



mere enclosing membrane with its nucleus flattened and pushed to one 

 side. At a certain stage each of the leishmania forms develops a flagellum, 

 and by gradual changes in the arrangements of its parts becomes trans- 

 formed into a crithidia form, and finally into a trypanosome of the blood 

 type (Fig. 207, 1-20). In any single group of organisms the change affects 



