GENUS: RHYNCHOIDOMONAS 375 



Diinkerly (1911) and Alexeieff (1911/, 1912e) also regarded these forms 

 as representing developmental stages of H. muscarum, which, however, is 

 most usually met with in the leptomonas form. Chatton (1913) expressed 

 the opinion that the flagellate, H. sp. (1) referred to below (p. 378), of the 

 Malpighian tubes of the adult Drosophila confusa had been evolved from 

 the intestinal species. Hence, he suggests that these Malpighian tube 

 forms should be placed in a distinct genus for which Patton's name has 

 priority. The type species of this genus, according to Chatton, will be 



g § r^ ^<:% ( 



9 



Fig. 174. — Life-Cycle of BhynchoUlomonas siphunculUue in Intestine of 

 Siphunculina funlcola (x ca. 2,000). (After Patton, 1921.) 



1-2. Pre-flagellate forms from stomach of fly. 



3-5. Growth of flagellate and formation of flagellum in Malpighian tubes. 

 6-9. Development of fully-formed flagellate of Rhynchoidomonas type in Malpighian tubes. 

 10-13. Retraction of flagellate forms towards the post-flagellate stage in Malpighian tubes. 



14. Post-flagellate stages which escape from the Malpighian tubes into the intestine and are 

 passed in the faeces. 



7?. drosophilcB [H. sp. (1)], which is said to occur only in the Malpighian 

 tubes of D. confusa. As many insect flagellates are known to occur in the 

 intestine, and occasionally in the Malpighian tubes {e.g., L. cteiiocephali 

 of the flea), it cannot be considered as finally established that the Mal- 

 pighian tube forms are distinct from the intestinal ones. 



Patton (1921) has given an account of what he regards as the complete 

 life-cycle of one of these forms, which he names R. siphunculince, and 



