Description of a Herpetomonas parasitic in the alimentary tract of the common green-bottle fly, Lucilia sp

Abstract

1. The parasite described inhabits the alimentary tract of two species of Lucilia. In addition it has a resting stage—the ‘cyst’—which is passed in the voided excrement of the insect.2. When the cyst is ingested by a fly it grows in length and becomes flagellated in the ‘crop’; in the midgut it greatly elongates and multiplies rapidly by division; in the hindgut it first shortens, then becomes spherical, and finally oval and cyst-like, meanwhile losing its flagellum.3. The cysts measure 3 μ, the fully flagellate forms 20 μ, in length.4. The cysts possess a cytostome and cytopharynx, the functions of which are probably nutritive.5. The flagellum consists of two parts (i) a cytoplasmic part, which probably subserves the power of movement and which I therefore propose to call the kinetoplasm, and (ii) a thread of chromatin secreted by the rhizoplast.6. The function of the chromatin in the flagellum is probably to sustain a filamentous form.7. The nucleus divides by a definite process something akin to mitosis.8. The chromidia serve as reserve material for the supply of chromatin in the cell. They are secreted probably by cell-plastids.9. I propose the name of this parasite be Herpetomonas luciliae, and that the genus Herpetomonas should be defined so as to include the forms described as Leptomonas.