198 Uiiirersitij of Cnlifornra PuhUcations In Zoologi) [Vol. ifi 



presumably have a parabasal body, still show two structures which 

 may be nucleus and parabasal body. The same may be said of the 

 forms in schizogony (Chagas, pi. 11, figs. 41-44, pi. 13, figs. 27-29). 

 In forms so minute, if a few of the merozoites exhibit both structures 

 it is safe to assume, at least as an alternative proposition, that they 

 are present in the other individuals as well, though they may be 

 obscured by their temporary position or conditions of staining. In 

 the closely allied but phylogenetically earlier forms, Herpctomonas 

 and Crithidia, Patton (1908), Porter (1909), and Wenyon (1913), 

 found the same conditions, that is, no stages in which the parabasal 

 body is habitually absent and no instance of its origin by heteropolar 

 mitosis of the nucleus. Prowazek (1904) describes a process of par- 

 thenogenesis with degeneration of the parabasal body in Herpeto- 

 monas muscac domesticae , but his figures are unconvincing in the ex- 

 treme. Results so entirely at variance with the observations of later 

 investigators cannot carry much weight. 



In Crithidia leptocoridas MeCulloch (1915) includes some doubt- 

 ful forms with the suggestion that there is some slight evidence of the 

 occurrence of two developmental forms not unlike those figured by 

 Chagas (1909) in the life-cycle of Schizotrypanum cruzi. As pointed 

 out above, the figures of Chagas do not bear out the interpretation 

 which he has placed upon them, and the case is not made stronger by 

 the comparison with the figures of Crithidia. The two developmental 

 forms of that flagellate, including the very questionable uninucleated 

 spores, must remain, for the present at least, as "doubtful forms," 

 as Miss MeCulloch has termed them. Further investigation may, per- 

 haps, reveal closer relations between them and the other stages, which 

 the data at hand fails to establish. 



The solution of the question of sexually difi'erentiated gametes and 

 of syngam^y in these forms has thus far proven elusive, and the re- 

 corded occurrence of bisexual gametes and sexual reproduction, as in 

 the ease of Trypanosoma lewisi as recorded by Prowazek (1905), may 

 be received with much skepticism. The fact that it has not been 

 found beyond dispute is not, of course, conclusive evidence against 

 its occurrence, but it is conclusive evidence in so far as the so-called 

 nuclear behavior of the parabasal body during conjugation is con- 

 cerned. The well-known instance described by Schaudinn in "Try- 

 panosoma" noctuae, cited by Hartmann, is very plainly the result of 

 a peculiar arrangement of pigment granules so common in these 

 forms. 



