The,presently accepted theory on the life cycle of T. cruzi. especially with regard to the genesis of the trypanosome form, is disputed. The trypanosome form does not develop from the crithidia by means of a diminution in size and a migration of the kinetoplast from its prenuclear position to the posterior pole of the cell (Brumpt, 1912), but it develops directly from round forms without intervention of the crithidial. The leishmania-like round forms and the intermediate stages between them and the trypanosomes were found in artificial cultures, Triatoma feces and the vertebrate host, and are descr. Their production is attributed to moderately unfavorable circumstances which obstruct and retard in a certain degree the successive binary fissions of the leishmanian, leptomonad and crithidial forms and favor processes of multiple division in them. The possibility of different mechanisms in the evolution of the trypanosome form should be admitted.