366 FAMILY: TRYPANOSOMID^ 



as a result of further observations, states that he has found this flagellate 

 in Madras in the following hosts: if. nebulo, M. humilis, Famiia canicu- 

 laris, Borborus sp., Drosophila sp., Lucilia argyricephala, L. craggi ; while 

 Becker {1923d) has shown by actual cross-infection experiments that in 

 North America it may infect Phormia regina, Lucilia sericata, Calliphora 

 erythrocephala, Cochliomyia {Clirysomyia) macellaria, Musca domestica, 

 and Sarcophaga bullata. He believes that H. ?nuscarum, H. lucilice, 

 H. callipliorcE, H. sarcophagce, and the Herpetomonas which occurs 

 naturally in P. regina and C. macellaria, belong to one species, 

 H. muscarum. The similar results obtained by Drbohlav (1925) have 

 been referred to above (p. 364). 



As regards the distribution of H. muscarmti in the fly, it may 

 occur in any part of the gut up to the opening of the proventriculus. 

 In the fully-grown leptomonas form it has a pointed, blade-like body 

 up to 30 microns in length and 2 to 3 microns in breadth. The flagellum 

 is often three times the length of the body. The nucleus is central in 

 position, and the elongated kinetoplast is near the anterior end, and con- 

 sists of the usual parabasal body, and the blepharoplast from which the 

 axoneme of the flagellum arises. The anterior end of the body is often 

 truncated or cut off, and a clear area may sometimes be seen to run 

 into the cytoplasm towards the kinetoplast. In some cases this clear, 

 funnel-like area appears to be continued past the kinetoplast, where it 

 terminates indefinitely in the cytoplasm. The fact that in some indi- 

 viduals structures like bacteria were seen at the posterior end of the body 

 led the writer (1913a) to suggest that this structure might be of the 

 nature of a cytostome. This, however, seems very doubtful, for Becker 

 (1923c) could detect no cytostome. It is found not only in the adult 

 leptomonas forms, but also in the shorter and broader types on the way 

 to encystment. 



A feature of this flagellate, which has given rise to some controversy, 

 is the frequent occurrence of two flagella (Fig. 169). This fact led 

 Prowazek (1904) to define the genus Herpetomonas as including biflagellate 

 organisms. The observations of Patton (19086), Porter (19096), Mackinnon 

 (1910), and the writer (1911a) have clearly shown that the biflagellate 

 individuals, which may comprise the majority of forms seen in an infection, 

 are in reality dividing forms (Fig. 159). When division is proceeding, 

 the blepharoplast elongates transversely, and a new axoneme growing 

 out of a new flagellum appears even before division of the blepharoplast 

 is completed. By the time the blepharoplast has divided, the new flagellum 

 may be as long, or nearly as long, as the original one. The daughter 

 blepharoplasts may proceed to division again, with a new axoneme forming 

 from each one, and this may occur before the parabasal or the nucleus 



