274 
Herpetomon ads 
EXPLANATION OF PLATE XIX. 
All the figures were outlined with Zeiss’ drawing-apparatus (Abbe), using Zeiss - r V' 
achromatic objective and ocular 4. 
Figs. 1—20 and 26—38 are stained with Giemsa’s stain, figs. 21—25 and 39—41 with 
iron-haematoxylin. 
Figs. 1—3. Pre-flagellate stages of herpetomonad from dung-flies. Fig. 1 is from mid-gut 
of larva of Homalomyia, sp. ?, figs. 2 and 3 from mid-gut of fly of Homalomyia and of 
Neuroctena anilis respectively. Giemsa. 
Fig. 4 (a and b). Pre-flagellates from mid-gut of flies of Scatophaga lutaria and Neuroctena, 
showing flagellum forming, (a) is surrounded by a cyst-wall: in (b) this has dis¬ 
appeared. Giemsa. 
Figs. 5—8. Further stages in formation of the flagellum. Giemsa. 
Fig. 9. Small flagellate. Giemsa. 
Fig. 10. Flagellate in which the body has not yet assumed the characteristic form. 
Giemsa. 
Fig. 11. Adult flagellate from mid-gut of fly ( Homalomyia) showing single flagellum and 
well-marked “ rhizoplast.” Giemsa. 
Figs. 12—16. Stages in longitudinal division of flagellates from flies of Homalomyia and 
Neuroctena , showing splitting of rhizoplast, upgrowth of second flagellum, and 
division of nuclei. Giemsa. 
Figs. 17—19. Further division stages from mid-gut of larva (Homalomyia) to illustrate 
precocious splitting of the body, with the resulting end-to-end arrangement of two 
individuals, one with a short and one with a long flagellum. Giemsa. 
Note: —Owing to the colours employed in the original drawing, the nuclei in 
Fig. 17 appear light instead of dark. 
Fig. 20. Sexual individuals in conjugation? From rectum of larva (Scatophaga). 
Giemsa. 
Fig. 21. Flagellate from mid-gut of larva ( Homalomyia ) showing tropho-nucleus in 
process of division. Iron-haematoxylin. 
Figs. 22—24. Further stages in division of flagellates from fly (Neuroctena). Note 
relatively small kineto-nucleus, well-marked tropho-nuclear karyosome, and absence 
of “ chromatoid ” granules in cytoplasm. Iron-haematoxylin. Cf. figs. 12—16. 
Fig. 25. Adult flagellate from mid-gut of fly (Neuroctena). Iron-haematoxylin. Cf. 
fig. 11. 
Fig. 26. Adult flagellate from mid-gut of larva (Homalomyia) showing small kineto- 
nucleus, short rhizoplast, and scarcity of “chromatoid” granules in cytoplasm. 
Giemsa. Cf. fig. 11. 
Figs. 27 and 28. Early division stages in flagellates from larva (Scatophaga). In fig. 28 
the rhizoplast is practically absent, the second flagellum has grown up almost to full 
length, and the tropho-nucleus shows a karyosome. Giemsa. 
Figs. 29—31. Flagellate individuals without tropho-nucleus. Fig. 29 from mid-gut of 
fly (Neuroctena) and figs. 30 and 31 from hind-gut of larva (Homalomyia). In fig. 29 
longitudinal division is taking place. Giemsa. 
Figs. 32—37. Stages in process of rounding up and encystment in hind-gut of fly. 
Figs. 34—37 show gradual withdrawal of flagellum and migration of kineto-nucleus 
into posterior portion of cell. Giemsa. 
Fig. 38. Large vacuolated cyst with thick, irregular cyst-wall. Giemsa. 
Figs. 39 and 40. Encysting stages. Iron-haematoxylin. Cf. figs. 34—-37. 
Fig. 41. Post-flagellates from hind-gut of fly (Homalomyia). Iron-haematoxylin. 
