294 
Flagellates in Fleas 
encystment that I saw is shown in Fig. 26. The cell is rounded off; 
the cytoplasm and the nucleus have taken on a more compact appear¬ 
ance ; the blepharoplast is indistinguishable from other deep-staining 
bodies in the cell ; the periplast stains faintly red, but there is no thick 
cyst-wall. 
Without actual observation of the process of conjugation, it seems 
rash to draw arbitrary distinctions between so-called “ male ” and 
“ female ” forms. It is evident, even from what I have indicated above, 
that complicated intracellular readjustments take place during the en¬ 
cysting stages of Herpetomonas ctenophthalmi and Crithidia liystricho- 
psyllae, but with such a limited material and no opportunity for close 
study of the living organism, it were unwise to force an interpretation. 
REFERENCES 1 . 
Balfour, A. (1906). Herpetomonas parasites in fleas. Journ. Hyg. vi. pp. 652-5, 
Plate i. 
-(1906). Second Report of the Wellcome Research Laboratories, Khartoum. 
Chatton, E. and Alilaire, E. (1908). Coexistence d’un Leptomonas {Herpetomonas) 
et d’un Trypanosoma ohez un muscide non vulnerant, Drosophila confusa, 
Staeger. Compt. rend. Soc. Biol. lxiv. p. 1004. 1 text-fig. 
Flu, P. C. (1908). Uber die Flagellaten im Darm von Melophagus ovinus. Archiv 
f. Protistenk. xii. pp. 147-53. 1 plate. 
IAger, Louis (1902). Sur un flagelle parasite de YAnopheles maculipeanis. Compt. 
rend. Soc. Biol. Liv. pp. 354-6. 10 figs. 
-(1903). Sur quelques Cercomonadines nouvelles ou peu connues parasites de 
l’intestin des insectes (note prdliminaire). Archiv f. Protistenk. II. pp. 186-7. 
4 figs. 
- (1904). Sur un nouveau flagelle parasite des tabanides. Compt. rend. Soc. 
Biol. lvii. pp. 613-5. 6 figs. 
-(1904). Sur les affinitds de 1’ Herpetomonas subulata, et la pbylogenie des 
trypanosomes. Ibid. pp. 615-7. 
Minchin, E. A. (1908). Investigations on the development of Trypanosomes in the 
tse-tse flies and other Diptera. Quart. Journ. Microsc. Set. lii. pp. 159-260. 
6 plates. 
Novy, F. G., Macneal, W. J., and Torrey, H. N. (1907). The Trypanosomes of 
Mosquitoes and other insects. Journ. Infect. Dis. iv. pp. 223-76. 7 plates. 
Patton, W. S. (1907). Preliminary Note on the life-cycle of a species of Herpetomonas 
found in Culex pipiens. Brit. Med. Journ. II. 78-80. 13 text-figs. 
-(1907). Insect flagellates. Ann. Report of King Inst it., Guindy, pp. 10-12. 
1 The complete literature on this subject may be found at the end of an article by 
Patton and Strickland on p. 343 of Yol. i. of this Journal. 
