Harold Mellor Woodcock

“ We cannot write quite so confidently with regard to the relation of the various pathogenic Trypanosomes to Tsetse-flies (Glossinae) . In the first place experiment has shown that biting-flies, other in all probability than the true, natural hosts, may at times transmit the parasites—as it were—accidentally, if, after feeding on an infected animal, they are allowed to bite a fresh one within a limited time. One very helpful factor in determining which is the principal carrier of any form is the coincidence of the zone of a particular insect with that of any disease. ”

“ The small Trypanosomes resulting from either of these modes of division differ from typical adults by their stumpy, pyriform shape, the position of the kinetonucleus near the flagellar end of the body, and the absence, during the first part of their youth, of an undulating-membrane. At this period they have, in fact, what may be termed a “pseudo-Herpetomonadine” aspect. These young individuals can themselves multiply by equal binary fission, giving rise to little fusiform parasites; with growth, these gradually assume the adult appearance. ”

“ The development of an indifferent ookinete into an indifferent Trypanosome is shown in fig. 7, from which it will be seen that the cytological details are very complex, The indifferent parasites exhibit an alternation of resting, attached phases with active periods, during which they multiply actively and become very abundant in the insect. The male forms, which are very small and the homologies of the micro gametes developed in the blood, appear to die off soon. The female Trypanosomes, on the other hand, grow to a large size, laying up a store of reserve nutriment. ”

“ Trypanosomes vary greatly with regard to size; even in one and the same species this variation is often noticeable, especially under Mon, , w, oD, different conditions of life. The common Trypanosoma rotatorium of frogs (fig., A and B) is, taking it all in all, one of the largest forms so far described. Its length (inclusive of the flagellum) varies from 40-60 p, while its greatest width (including the undulating-membrane) is from 8-30, a; in the very wide individuals breadth is gained more or less at the expense of length. ”

“ Agglomeration consists in the grouping or union together of several Trypanosomes around a common centre; this leads to the formation of rosette-like clusters, or even of large masses composed of several rosettes. The end by which the parasites join is typically, in the case of Trypanosoma, the non-flagellate (anterior) end. If a favourable change in the surrounding medium sets in, the Trypanosomes are able to undergo the reverse process, namely dis agglomeration; the parasites liberate themselves and the rosette is dissolved. ”

“ In considering the occurrence of Trypanosomes in mammals, careful distinction must be drawn between natural or true hosts, which are tolerant of the parasites, and casual ones, which are unaccustomed and unadapted to them. A Trypanosome usually produces markedly harmful effects upon gaining an entry into animals which have never been, by their distribution, liable to its invasion previously. ”

“ The Trypanosomes, in the active phase, are of course always free in the blood plasma (interglobular) . In the majority of cases it is very uncertain whether they actually come into relation with the blood corpuscles or not. Schaudinn has stated, however, that Trypanomorpha becomes, in certain phases, attached to a red blood-corpuscle (ectoglobular) , and, in others, penetrates inside one and eventually destroys it (endog1obular) ; while his other avian parasite, Trypanosoma ziemanni, apparently draws up into itself the white corpuscle (leukocyte) to which it becomes attached. ”

“ Such a state of affairs is produced by the march of civilization into the “hinterlands” of the various colonies, when man, together with the numerous domesticated animals which accompany him, is brought into proximity to big game, &c., and, what is equally important, into the zone of the particular blood-sucking insects which prey upon the same. ”

“ One flagellum is entirely free and directed forwards; the other at once turns backwards and is attached to the convex or dorsal side of the body for the greater part of its length. In all other Trypanosomes there is only one Hagellum, which is invariably attached to the body in the same manner as the posterior one of bi flagellate forms. ”

“ Schaudinn (50) , who investigated certain avian Trypanosomes, considered the latter View to be correct, and believed, that the carrier—in this instance a gnat—is indeed the definitive host, i.e. the one in which sexual conjugation occurs. Many other workers have since studied the subject and, so far as the parasites of fishes are concerned, there can be little doubt, thanks to the researches of E. Brumpt (5a) , L. Léger (32, 33) and others, that leeches are true alternate hosts for these forms, in which certain phases of the life-cycle are normally undergone. ”

“ The parasites are frequently more numerous in the spleen, bone-marrow, kidneys, &c., than elsewhere, and it has been found that multiplication goes on rather more actively in the capillaries of these organs. ”

“ These are undoubtedly the organs which react most strongly to the parasites, and their enlarged condition is to a great extent due to their enhanced activity in elaborating blood-corpuscles and leukocytes to cope with the enemy. Ingestion and dissolution of the Trypanosomes by phagocytes has frequently been observed ”

“ Trypanosomes are harboured by members of all the chief classes of vertebrates with the exception of cyclostomes. By far the greater number of hosts are furnished by fishes, birds and mammals. Among batrachians the parasites have been found, up till now, only in frogs; and among reptiles their occurrence has only been observed in one Occurrence. ”

“ Not only is there an intimate correspondence in this respect between the two principal organelle, but the flagella apparatus itself is really of nuclear origin and remains closely connected with the kinetonucleus (cf. fig. 7) . In most cases, however, little-beyond the position and general appearance of the nuclei has been so far made known. The trophonucleus is usually situated somewhere about the middle of the body. The kinetonucleus is typically near the anterior end ”

“ Family: Trypanosomatidae, Doflein.-Flagellates, in the great majority of instances haemal parasites, derived from a bi flagellate, Buda-like type, in which the posteriorly-directed (trailing) flagellum is always present and attached to the body by an undulating membrane, of which it constitutes the thickened edge. The other, the anterior flagellum, may or may not persist.
Genus Trypanoplasma, Lav. and Mesnil, 1902.—The anterior flagellum is present. Both flagella are inserted close together, near the anterior end of the body. Two sub-groups may be' distinguished. ”

“ C) ; in Trypanomorpha it is in the posterior half of the body (fig. 3, E) . In certain forms the occurrence of prominent myonemes or muscle-fibrillate has been described, and, moreover, a nuclear origin assigned to them also. In Trypanomorpha they are confined to the undulating-membrane (fig. 3, E) , but in other cases—Trypanosoma ziemanni, T. lewisi, T. brucei, and T. soleae-they are arranged laterally, half running down each side of the body (fig. 4, J) . In Trypanoplasma borreli there is only a single myoneme on either side. ”

“ They are very sluggish and do not divide. They are the most resistant to unfavourable conditions of environment, and are able, by a process of parthenogenesis, to give rise to ordinary, indifferent forms again, which can repopulate the gnat. ”

“ T. equinum, Voges, causing mal de caderas or “hip-paraplegia” in South America (fig. 3, D) ; T . theileri, Lav., a very large form, the cause of galziekté or bile-sickness to cattle in the Transvaal; and T. gambiense, Dutton (syn. T. ugandense, Castellani, T. castellanii, Kruse) , the cause of human trypanosomosis in central Africa, which becomes sleeping-sickness when the organisms penetrate into the cerebro-spinal fluid (fig. 3, C) .
Parasitic in birds: T. avium (Danil., Lav. emend.) ”

“ 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) ”

“ Arb. kais. Gesundheitsamte (1905) , 22, 44 pp., pls.; (48) L. Rogers, “On the development of flagellated organisms (Trypanosomes) from the spleen Protozoic parasites of cachexial fevers and Kala-azar,” Quart. Journ. Mic. Sci. (1904) , 48, p. 367, 1 pl.; (49) R. Ross, “Notes on the bodies recently described by Leishman and Donovan,” Brit. Med. Journ. (1903) , i. 1261, 1401, figs.; (50) F. Schaudinn, “Generations- und Wirthswechsel bei Trypanosoma und Spirochaete,” Arb. kais. Gesundheitsamte (1904) , 20, p. 387, figs.; (51) idem, “Zur Kenntniss der Spirochaete pallida,” Deutsch. med. Wochenschr. ”