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Rh Leishman’s form, and there is no doubt that the parasites are closely allied to that type of organism. This does not, however, preclude in any way the supposition that they-equally with certain other Haemosporidia-represent, nevertheless, only a phase of a complete life-cycle; and this supposition has in act been definitely proved to be true by the work of Rogers (48). Rogers cultivated the parasites obtained from cases of kala-azar in artificial media, and found that what were unmistakably flagellate stages developed in the cultures at different intervals (fig. 8, IV. e, f, g). These forms were elongated and spindle-like; and to one end of the body, near which the smaller nuclear element was situated, a well-developed flagellum was attached. Since then many other workers have obtained similar stages [see Leishman and Statham (38), Christophers (7)]; but however slender and Trypanosome-like the flagelliform parasites may appear, up till now no indications of an undulating membrane have been seen, and the kineto-nuclear element is never far from the insertion of the flagellum.


 * . 8.

I. Piroplasma (Leishmania) donor/ani, Lav. and Mesnil. a, Typical pear-shaped or oval forms; b, various stages in longitudinal division; c, nuclear division preparatory to multiple fission; d, endoglobular forms, in red blood-corpuscles (p=pigment grains); e, bacillary form of the parasite in a corpuscle; M, large macrophageal cell with many parasites (after Donovan).

II. Uninuclear leukocyte (L) containing several parasites (after Lav. and Mesnil).

III. P. (Heleosoma) tropicum (Wright).

a, Single individuals; b, dividing forms (from Mesnil, mostly after Wright).

IV. P. donovani in cultures of different ages. a, Ordinary forms of varying sizes; b c, stages in multiple division; d, binary fission; e, f, g, flagellate forms (after Rogers).

Nevertheless, the general appearance and structure of these motile forms so greatly resemble that of a Herpetomonad, or of the “pseudo-Herpetomonadine” forms of a Trypanosome which are 0btai'ned in cultures, that it cannot be doubted that the “ Leishman-Donovan-Wright” bodies are closely connected with the Haemofiagellates. That being so, it is quite possible that, in normal conditions and circumstances, these parasites also possess, at some period of the life-cycle, a trypaniform phase. Nothing definite is yet known with regard to the transmission of the parasites by an alternate invertebrate host, although there is presumptive evidence in favour of this supposition.

A word or two must be said in conclusion with reference to the supposed connexion of the S pirochaelae with the Trypanosomes. In Schaudinn's great memoir he regarded Trypanosoma ziemanni as possessing, in certain phases, the actual characteristics of a Spirochaete as then known; and, further, he was songs' inclined to think that other Spirochaetae (e.g. S. obermeieri of relapsing fever) were also only phases in the life-cycle of a particular Haemoflagellate. As a result of his more recent investigations on S. plicatilis (the type-species of Ehrenberg) and other forms (51), he finds, however, that this is not the case, but that the organisms exemplified by S. plicalilis are to be widely separated from the Trypanosomes, and placed rather with the Bacteria. In addition, it is most probable that, at any rate, certain other spirilliform parasites, e.g. S. balbianii, S. refringens, agree fundamentally in structure with the type-species.

On the other hand, evidence has lately been brought forward to show that certain parasites which greatly resemble a Spirochaete are really related to the Trypanosomes. This is the case with the celebrated organism first described by Schaudinn and E. Hoffmann (52) from essential syphilitic lesions, and now known as Treponema (Spirochaete) pallida, Schaud. F. Krzysztalowicz and M. Siedlecki have published an important account (17) of this parasite, which they consider possesses a true trypaniform phase, and for which they have proposed the name Trypanosoma luis. This view requires, however, corroboration. Nevertheless the resemblance between the biology of this organism in relation to syphilis (as regards mode of infection, habitat, &c.) and that of Trypanosoma equiperdum, the cause of dourine or “horse-syphilis,” may not be without significance.

.—A comprehensive review of the Haemoflagellates and allied parasites, considered up to the end of 1905, has been published by (1) H. M. Woodcock, ''Quart. Journ. Mic. Sci.'' (1906), 50, p. 150. The principal original papers referred to are: (Ia) A. Billet, “Culture d’un trypanosome de la grenouille chez une hirudinée,“ &c., ''C. r. ac. sci. (1904), 139, p. 574; (2) “Sur le Trypanosoma inopinatum'' de la grenouille verte d’Algérie et sa relation possible avec les Drepanidium,” C. r. soc. biol. (1904), 57, p. 161, figs; (3) 1. R. Bradford and H. G. Plimmer, “The Trypanosoma brucei, the organism found in Nagana or the Tsetse-Hy disease,” Quart. Journ. Mic. Sci. (1902), 45, p. 449, with pls; (4) D. Bruce, D. Nabarro and E. D. Greig (various reports on sleeping-sickness and other trypanosomoses in Uganda), Roy. Soc. Comm. (1903-1905), Nos. 1, 4 and 5; (5) E. Brumpt, “Contribution a l’étude de l’evolution des hémogregarines et des trypanosomes,” C. r. soc. biol. (1904), 57, p. 165; (5a) idem, “On the mode of transmission and development of Trypanosomes and Trypanoplasms in leeches,” C. r. soc. biol. (1906), 60, pp. 160, 162; and op. cit. (1906), 61, p. 77; (6) A. Castellani, “Trypanosoma and Sleeping-sickness,” ''Rep. Sleeping-sickness Comm. Roy. Soc.'' (1903), Nos. 1 and 2; (7) S. R. Christophers, “Reports on parasite found in persons suffering from enlargement of the spleen in India,” Sci. Mem. India (1904–1905), Nos. 8, 11 and 15; (8) Danilewsky, “Recherches sur la parasitologie comparée du sang des oiseaux (Kharkoff, 1888-1889); (9) D. Doflein, Die Protozoen als Parasiten und Krankheitserreger, (Jena [G. Fischer], 1901); (10) C. Donovan, “Human Piroplasmosis,” Lancet (1904), p. 744, 1 pl.; (11) E. Dutton, “Note on a Trypanosoma occurring in the Blood of Man, “Brit. Med. Journ. (1902), p. 881; (12) Dutton and J. L. Todd, “First Report of the Trypanosomiasis Expedition to Senegambia, 1902, “Mem. ''Livpl. Sch. Trop. Med. (1903) 11; (13) Gruby, “Recherches et observations sur une nouvelle espèce d’Hématozoaire (Trypanosoma sanguinis)” C. r. ac. sci.'' (1843), 17, p. 1134, also Ann. sci. nat. (1844), 3, i. p. 105, figs.; (14) W. Hanna, “Trypanosoma in Birds in India,” Quart. Journ. Mic. Sci. (1903), 47, p. 433, 1 pl.; (15) G. Keysselitz, “Über Trypanophis grobbeni (Trypanosoma grobbeni, Poche),” Arch. Protistenk. (1904), 3, p. 367, figs.; (16) idem, “Generations- und Wirthswechsel von trypanoplasma borreli, Lav. u. Mesnil,” op. cit. 7, p. 1, figs.; (16a) R. Koch, “Mittheilungen Uber den Verlauf der deutschen Expedition. . in Ostafrika,” Deutsch. med. Wochensch. (1906), app., p. 51; op. cit. (1907), p. 49; (17) F. Krzysztalowicz and M. Siedlecki, “Contribution à l’étude de la structure et du cycle évolutif de Spirochaete-pallida, Schaud.,” ''Bull. Ac. Cracovie'' (1905), p. 713, 1 pl.; (18) E. R. Lankester, “On Undulina, the type of a new group of Infusoria, “''Quart. Journ. Mic.'' Sci. (1871), 11, p. 387, figs.; (19) “The Sleeping-sickness,” Quart. Rev. (July 1904), p. 113, figs.; (20) A. Laveran, “Sur un nouveau trypanosome des bovidés,” C. r. ac. sci. (1902), 134, p. 512; (21) idem, “Sur un trypanosome d’une chouette,” C. r. soc. biol. (1903), 55, p. 528, figs.; (22) idem, “Sur un nouveau trypanosome d'une grenouille,“ op. cit. (1904), 57, p. 158, figs.; (23) Laveran and F. Mesnil, “Recherches morphologiques et expérimentales sur le trypanosome des rats, Tr. Zewisi (Kent),” Ann. inst. Pasteur (1901), 15, p. 673, zpls.; (24) idem, “Des Trypanosomes des poissons, " Arch. Protistenk. (1902), 'I, p. 475, figs.; (25) idem, “Recherches morphologiques et expérimentales sur le trypanosome du Nagana ou maladie de la mouche tsé-tsé,” Ann. inst. Past. (1902), 16, p. 1, figs.; (26) idem, Trypanosomes et trypanosomiases (Paris [Masson et Cie], 1904); (27) idem, “Sur un protozoaire nouveau (Piroplasma