SIX IN PROIOZOA 147 



(^rlicr nicnibcrs of rhc Trvpniiosoniiuidac have been credited 

 with sexLiaUtw Fki (1908) described "male" and "fenvale" stages in 

 a leptomonad flagellate from the gut of Melophagiis ovinus. Although 

 he saw no "copulation," certain stages were interpreted as being 

 "ookinetes." 



Adie (1921) reported "conjugation" between free flagellates of 

 Leisbviaiiia douovani in gut cells of the bedbug, Civiex kctular'ms, 

 which had been fed on spleen juice from a case of kala azar. Patton 

 (1922) stated that he had conflrmed the intracellular stages reported 

 bv Adie, but \\'enyon (1926) remarked that the bugs died after 

 feeding on the spleen juice and were then placed in an incubator at 

 27 "C. The developmental stages were found about 36 hours after- 

 wards. He thought that the observed development was more like that 

 in a culture than that in a vector and was skeptical of the interpreta- 

 tions given. 



Although there appears to be a considerable amount of evidence 

 for cell fusions in members of the Trypanosomatidae, it must be con- 

 fessed that the observations reported are usually capable of inter- 

 pretations other than "sexual," and in no case are the so-called "sex- 

 ual" phenomena complete with satisfactory chromosome counts and 

 meiosis. 



In the somewhat related Cryptobiidae there are several accounts 

 of sexual reproduction. The most convincing is that of Belaf (1916), 

 who repudiated his interpretation in 1926. 



Possibly the earliest accounts of cell fusion in free-living mem- 

 bers of the Protomonadina were those of Dallinger and Drysdale for 

 several small unnamed flagellates (1873a,b; 1874a,b), in addition to 

 one with the characters of Folytovia (1874c), and the "calycine 

 monad" (1875), which apparently was Tetramitus rostratus. Cell 

 fusion was followed by encystment. At excystment, large numbers 

 of small granules wxre released which, according to the authors, grew 

 more or less rapidly to the adult condition. A\ hile evidence for cell 

 fusion might be accepted, the formation of large numbers of minute 

 granules which grow into adult flagellates has not been confirmed. 



Additional accounts of fusion of ordinary cells followed by en- 

 cystment have been given for a number of protomonads, for exam- 

 ple, for Monas vivipara (Prow^azek, 1903); Bodo lacertae (Prowazek, 

 1904b); Moims ternio (Martin, 1912); Helkesi77iastix faecicola (Fig. 

 E, 1 to 6) (Woodcock and Lapage, 1915); Cercomoiias lovgicatida 



