376 FAMILY: TRYPANOSOMID^ 



which occurs in the Malpighian tubes of the eye fly, Sijiliunculina funicola, 

 of Madras (Fig. 174). The life-cycle which he describes follows closely 

 those of other arthropod flagellates studied by him (Fig. 166). The pre- 

 flagellate stage resulting from ingested cysts occurs in the stomach of the 

 fly, but, unlike the pre-flagellate forms of species of leptomonas and 

 crithidia, these do not reproduce, but merely increase in size, while the 

 axoneme becomes evident. Further growth takes place only in the 

 Malpighian tubes, where the typical rhynchoidomonas forms are produced. 

 When fully formed, these may measure 55 microns in length. The nucleus 

 lies nearer the anterior than the posterior end, and the kinetoplast lies 

 near but posterior to the nucleus. From the kinetoplast the axoneme 

 passes to the anterior end along the surface of the body. A definite 

 undulating membrane is not developed, nor is the axoneme continued 

 beyond the anterior extremity of the body. The part of the flagellate 

 behind the nucleus varies considerably in length according to the stage 

 of development. At first it is quite short, but in the fully-formed flagel- 

 lates it may be drawn out into a long, tapering, cytoplasmic process three 

 or four times as long as the portion of the body anterior to the nucleus. 

 Multiplication takes place by longitudinal division after division of the 

 kinetoplast and nucleus, but, contrary to what usually occurs in other 

 Trypanosomidse, the body commences to divide at the posterior ex- 

 tremity. After the flagellate stage has been reached, development 

 towards the post-flagellate takes place. The long posterior portion of 

 the body is withdrawn, and forms very much like pre-flagellate stages 

 arise. In some of these the kinetoplast is near the posterior extremity 

 of the body, and the nucleus nearer the anterior end. These forms are 

 attached to the cells of the Malpighian tubes in clusters. Eventually, 

 small rounded or oat-shaped forms are developed, and these escape into 

 the gut and are excreted with the faeces. Patton was able to demonstrate 

 that this flagellate never developed in the larvae of the fly which were fed 

 on the dead bodies of adult flies harbouring this parasite. On the other 

 hand, another form (Herpetotnonas siphunculincB), which occurred in the 

 intestine of the fly, readily infected the larvae and appeared in the intestine 

 of the adult. The fact that typical trypanosome forms with free flagella 

 occurred in the cycle of the H. siphunculincB in the intestine of the fly, 

 and that this flagellate was never found in the Malpighian tubes, raises the 

 question of its relationship to the rhynchoidomonas form, which may be 

 a stage of evolution of H. siphunculincB. The peculiar features of its 

 morphology may be due to the fact that it has invaded the Malpighian 

 tubes, which is not its usual habitat. The writer cannot agree with 

 Patton that the rhynchoidomonas forms are not of the trypanosome type. 

 It is known that in typical trypanosomes, as, for instance, T. lewisi 



