Trypanosoma cruzi does not reproduce itself in the leech (Haementerm lutzi Pinto); the ingested trypanosomes degenerate after some time; other organisms remain apparently normal, however dying 48 hours after the feeding of the leechs. The parasite trypanosomas of the frog (T. rotatorium and T. leptodactyli) as well as those parasiting the ophidian Rachidelus brazili (T. hogei) do not multiply in the intestine of the triatominae. The most resistent species (T. leptocbactyli) remains alive 72 hours after the feeding of the triatominae; the other two, however, do not survive more than 24 hours.
