Flagellate

“ You will, however, see that by studying these flagellates along these lines it is easy to work out their complete life-histories, and, above all, to find out how they pass from one host to another. In the case of H. muscae domesticae in Madras the flagellate and postflagellate stages are readily found, but owing to the fact that a large number of flies have to be examined before the preflagellate stages can be studied, this important portion of the life-cycle of the parasite is very apt to be missed. ”

“ Confusion is further likely to arise since herpetomonads pass through pre-flagellate, flagellate and post-flagellate or encysted stages; pre- and post-flagellate stages being oval or rounded and Leishmania-like. The post-flagellate stages are shed in the fæces, and are the cross-infective stages by means of which new hosts are infected by the mouth. The possible presence of such natural flagellates must always be considered when experimenting with fleas, lice, mosquitoes, etc., as possible vectors of pathogenic flagellates like Leishmania and Trypanosoma. ”

“ In Madras about 100 per cent, of flies, caught in the bazaar meat shops, are infected with it, and as a result of my observations on the living parasite as well as in stained preparations, I am unable to accept Prowazek's view of its flagellar apparatus, for I find the adult flagellate has a single flagellum. I can only assume that Prowazek happened to examine flies in which the majority of the adult flagellates were undergoing the early stages of simple longitudinal division ”

“ It is quite a common thing to find nearly all the adult flagellates in a fly exhibiting this appearance of a double flagellum. If the mid-guts of a number of flies are next examined in the fresh condition, in some, the flagellates will be seen collecting together towards the rectum, they attach themselves in rows by their flagellar ends to the gut-wall, and now further changes are seen to occur. ”

“ I also provide new perspectives on the evolution of bacterial flagella and the cell envelope and conclude that the last common ancestor (cenancestor) of all life was a highly developed non-flagellate Gram-negative eubacterium with murein cell walls, acyl ester phospholipids, and probably non-oxygenic photosynthesis and gliding motility. ”

“ An anterior lateral trailing flagellum may modify this axial rotation, and help in steering. When the animal is at rest—attached by its base or with its body so curved as to resist onward motion—the current produced by the tractellum will bring suspended particles up against the protoplasm at its base of insertion. As noted by E. R. Lankester, the posterior flagellum of many Haemoflagellates, like that of the spermatozoon of Metazoa, propels the cell by a sculling motion behind ”

“ Certain South American species of the family Reduviidae are disease carrying and there is evidence the conenoses in San Diego County, California, are infected with a disease-producing flagellate. Lack of large bug populations in close contact with man and ineffective transmission habits protect man in the Southwest from disease contacts. However, the site of the bug’s bite becomes inflamed, and swelling may spread over an area up to a foot in diameter. ”

“ 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. ”

“ It was greatly advanced by the method of double staining (with alkaline methylene blue and eosin) introduced by Romanowsky (1891) and elaborated by Ziemann, Leishman, Giemsa and others. By this means the presence of a terminal flagellum and of an undulating membrane at the side of the flattened and extended body was demonstrated. Laveran and Mesnil (1901) discovered allied flagellates in the blood of the fish, Scardinius erythrophthalmus. These flagellates, now placed in the genus Trypanoplasma, had a second free flagellum in addition to the one bordering the undulating membrane. ”

“ One nucleus only, which may be compact or vesicular, is known in many species. This nucleus is situated either centrally or sometimes near the flagellar end of the body, but its position is subject to variation. The flagella may arise near the nucleus. Other structures, such as an axial filament and a rhizoplast, may be present. Some flagellates are binucleate, the two nuclei—which often differ in size and shape—being separated from each other. One of these nuclei is the principal, vegetative or trophic nucleus ”

“ In addition there is an undulating membrane, bordered by a trailing flagellum, that commences at the anterior extremity and proceeds obliquely backwards. The nucleus, which is vesicular, is situated near the anterior extremity, and behind it are one or more vacuoles, none of which seems to be contractile. These flagellates are parasitic in vertebrate animals, and live chiefly in the intestine. ”

“ In some, a symbiosis occurs with Zooxanthella, Brandt, a Flagellate of the group Chrysomadineae, which in the resting state inhabits the extracapsular cytoplasm growing and dividing freely therein, and only (under study) becoming free and flagellate on the death of the host (fig. III. 4, 6-13) . ”

“ Herpetomonas is a generic name for certain flagellates possessing a vermiform or snake-like body, a nucleus placed approximately centrally, and a blepharoplast (kinetic nucleus) near the flagellar end. There is no undulating membrane (fig. 49, a) . The organisms included in this genus certainly possess one flagellum, while according to Prowazek (1904) Herpetomonas muscæ-domesticæ, the type species, possesses two flagella united by a membrane. ”

“ If you make a preparation of malarial blood from a patient by pricking the finger and spreading a little of the blood on a slide, fixing it immediately with heat or alcohol and staining it, you will never see any of these flagellated organisms. But if the slip be kept moist and in a warm temperature for half an hour and then stained, the flagellated bodies will be seen, proving that they develop only after the escape of the parasite from the human body. Such a fact is very interesting and obviously has some significance in connection with the life of the parasite. ”

“ Being a parasite, the germ of malaria, to keep in existence as a species, must pass from host to host; in other words, must at some time have an extracorporeal life. From the fact that the flagellated body does not come into existence until the blood has left the blood-vessels— that is, until it is outside the body I concluded that the function, then unknown, of the flagellum lay outside the human body, and that the flagellated body was the first phase of the extracorporeal life of the malaria parasite. ”

“ The body may be naked or corticate. The only organisms which concern the soil biologist belong to the Flagellata order.
The Flagellates differ considerably among themselves, both as regards their mode of feeding, and the number of flagella, thus making their classification difficult and outside the scope of this book. Suffice it to say that in the soil such organisms occur possessing one, two, three or four flagella, ex. Oicomonas termo, Heteromita globosus, Dallengeria and Tetramitus spiralis. ”

“ Genus. Cercomonas, Dujardin emend. Bütschli.
Oval or rounded organisms, with the aflagellar end often drawn out into a tail-like process.
Cercomonas hominis, Davaine, 1854.
Davaine found flagellates in the dejecta of cholera patients. They had pear-shaped bodies, lengthening to a point posteriorly. Their length was from 10 μ to 12 μ, and a flagellum about twice as long as the body projected from one extremity (fig. 21) . A nucleus was hardly recognizable. Occasionally a somewhat long structure (cytostome?) appeared at the anterior extremity. The animals moved with remarkable activity. ”

“ Division is initiated by that of the blepharoplast and nucleus. The division may be equal or subequal, whereby differences in size of individuals partly arise. Multiple division by repeated binary fission, without complete separation of the daughter forms, is known in some trypanosomes (e.g., T. lewisi) , and rosettes of parasites thereby are produced (fig. 27) .
The classification of trypanosomes is very difficult. Laveran (1911) 54 has suggested the examination of the relative length of the flagellum as a diagnostic character, and so arranged these flagellates in mammals in three groups. ”

“ Probably, although I have not experimented with this object in suitable cases, the eruption of microgametes will be favoured in the non-crescent-forming parasites by similar means.
In certain bloods the flagellated body is easily procured; in others the opposite is the case. As regards the crescents, doubtless success depends in a measure on the degree of maturity of the parasite, young or effete crescents failing to evolve. ”

“ Chagas thinks that the gametes for the cycle in Lamus arise from parasites developing in the lungs of the vertebrate host. Flagellated parasites enter the lungs, lose the flagellum and become oval in shape, later on dividing into 8 parts. These assume an elongated form and enter the red cells of the host. Against this is the statement of various observers that the flagellates are only to be found free in the plasma, never within red cells. The forms taken up by Lamus multiply in the intestine and then pass to the salivary glands after about 8 days. ”

“ The fact that many of these blood-flagellates (if not all) have, besides their life in the blood of one species of animal, a second period of existence in the juices or the gut of another animal, has made it very difficult to trace their migrations, since in the second phase of their history their appearance differs considerably from that which they presented in the first. ”

“ TRYPANOSOMES, or Haemoflagellates, minute Protozoan parasites, characterized by the possession of one or two flagella and an undulating membrane, and specially adapted for life in the blood of a vertebrate. [1] Of late years considerable progress has taken place in our knowledge of these organisms, research upon them having been stimulated by the realization of their extreme importance in medical parasitology. ”

“ Opalina (Fig. 41, p. 123) , however, and most Flagellates are "positively galvanotactic," and move towards the anode. H. H. Dale [32] has shown that the phenomenon may be possibly in reality a case of chemiotaxy, for the direction of motion varies with the nature and concentration of the medium. ”

“ DINOFLAGELLATA, so called by O. Bütschli (= the Cilioflagellata of E. Claparide and H. Lachmann) , a group of Protozoa, characterized as Mastigophora, provided with two flagella, the one anterior extended in locomotion, the other coiled round its base, or lying in a transverse groove. The body is bounded by a firm pellicle, often supplemented by an armour (“lorica”) of cuticular cellulose plates, with usually a marked longitudinal groove from which the anterior flagellum springs, and an oblique or spiral transverse groove for the second flagellum. ”

“ There is a small cytostome near the roots of the flagella. There is a well-marked karyosome in the nucleus. The movement is jerky. The shorter, anterior flagellum may be used in food-capture. In life, bacteria have been seen to be ingested. Food-vacuoles tend to accumulate at the posterior (aflagellar) end. A contractile vacuole may be present, near the base of the cytostome, and may really be the dilated fundus of the latter. Division occurs by binary fission. The organism can encyst (fig. 25, a) , when the flagella are lost, and round or oval cysts are found, 5 μ to 7 μ in diameter. ”

“ The Whip-swimmers (Flagellata) , which we consider as a third class of the kingdom Protista, are of no less doubtful nature than the Amœbæ. They often show as close and important relations to the vegetable as to the animal kingdom. Some Flagellata at an early stage, when freely moving about, cannot be distinguished from real plants, especially from the spores of many Algæ; whereas others are directly allied to real animals, namely, to the fringed Infusoria (Ciliata) . The Flagellata are simple cells which live in fresh or salt water, either singly or united in colonies. ”

“ Cell-wall firm not gelatinous, rarely forming colonies. Fore-end of the body with two or four (seldom five) flagella. Almost always green in consequence of the presence of a very large single chromatophore. Generally a delicate shell-like envelope of membranous consistence. 1 to 2 simple contractile vacuoles at the base of the flagella. Usually one eye-speck. Division of the protoplasm within the envelope may produce four, eight or more new individuals. ”

“ Bütschli’s theory of Protozoan phylogeny implies that a flagellum is an organ of most primitive nature, possessed perhaps by the earliest forms of life; and it must be remembered that flagella are borne by many Bacteria. On the other hand, one would imagine, from general considerations, that living beings possessing a flagellum would have been preceded in evolution by others that did not bear so definite an organ. ”