LTFE-HrSTOKY OF LRL'TOMONAS MUSf'.^- DOMRSTIf'.F. 649 



inonas (fig. 2), whicli nctively divides in the intestine or in 

 the Malpig-hifui tubules of the fly (figs. 6-10), producing- 

 (2) veiy active, slender foi-nis^ often with undulating mem- 

 brane (figs. 11-14). These probably encyst while attached in 

 large numbers to the rectal wall, and the cysts (figs. 15 and 

 17a) may be passed out with the fa3ces to give rise to flagellate 

 forms in another fly, as described by Patton (19) for the 

 Herpetomonas (? Leptomouas) of Musca nel)ulo, the Madras 

 bazaar fly. But whether the lai-ge Hei-petomonas form {i\<^. 1) 

 should have a {)lace in this life-history I am at present unable to 

 decide. Almost certainly the above is but a part of the whole 

 life-cycle, and the low percentage of infectious have prevented 

 the completion of it up to the present. It might be thought 

 improbable on a priori grounds that flies in England and in 

 India should be infected by the same pair of parasites, yet in 

 smears of house-flies' guts which Dr. Row brought from India 

 and kindly left at the Ijister Institute, there ai-e large 

 Herpetomonads and small Leptomonads just as in H . cani- 

 cular is in England. If these should prove to be dilferent 

 forms of the same organism, and at the same time have a 

 trypanosorne-stage in their life-histor}-, considerable changes 

 in our nomenclature of flagellate parasites will be necessitated. 



As to Prowazek's description of elaborate autogamy and 

 hereditai-y infection in Herpetomonas, one is tempted to 

 intei'pret some of his figures (which hardly bear out his 

 accouut), as being those of a Sporozoan infection, and I 

 hope to publish shortly an account of a Microsporidian which 

 I have found in Homalomyia. 



The nomenclature of these forms, interesting on account of 

 their probable relationship with the trypanosomes, isin a very 

 confused state, and it is with a view to the clearing up of at 

 least one part of the vexed question that I wish to re-state the 

 following facts in their history. 



Saville Kent in 1881 (23) established the genera Lepto- 

 monas and Herpetomonas for uniHagellate parasites found in 

 a Nematode, Trilobus, and in Musca dom estica respec- 

 tively. The only points of distinction mentioned by him 



