When examining the contents of the alimentary canal of caddis-fly larvae, I found that in addition to certain well-known gregarines, they generally harbour several other interesting protist parasites which have not hitherto been described. Chief among these are: (a) a tricho-mastix, (b) a spirochaete, and (c) a flagellate which appears to be related to Macrostoma caulleryi, Alexieff. The present paper deals with the trichomastix and the spirochaete: I hope to describe the other flagellate fully in a future communication.

The foregoing comparison of the anatomy of the apterous viviparous and the winged viviparous stages of S. rosarum although not revealing any very great differences, may be regarded as supporting the view that the apterous stage is a degeneration from the winged stage. The fact that so much similarity exists between the two forms is perhaps more easily explained by supposing that the habit of flight had become eliminated, possibly through disuse, resulting in the consequent atrophy and disappearance of the organs directly concerned with that function; for if the other view be considered, it would be reasonable to suppose that more specially marked differences in an upward direction would be the result of such a vital change in the habit of the creature. There is one point of difficulty, however, and that is to account for the difference in form of the alimentary canal, but, as has been already suggested, this may be due to other, quite different, and at present unknown, causes.

In an earlier paper (Nuttall, Fantham and Porter, 1909, Parasitology vol II. pp. 325—340), we recorded our observations on living Theileria parva as seen in the peripheral blood of two cows which succumbed to East Coast Fever1. We now propose to describe our studies upon the parasite in stained preparations made from the animals' blood during the course of the disease and from their organs shortly after death. We shall confine our attention to the types of parasites encountered within red blood corpuscles or to corresponding types which may be occasionally encountered free in the plasma. The subject of “Koch's blue bodies” will receive attention at a later date.

A small but extremely interesting collection of Ticks and other Arachnids was brought over from Ceylon by Mr C. C. Dobell in 1909, and was supplemented by a few tubes sent subsequently by Dr A. Willey from the same island. While these were being examined, a large consignment of ticks was received from the Indian Museum, Calcutta, being in fact the whole collection of the museum. The two collections may be conveniently dealt with in the present paper, which will give a list of the species they respectively contain, and a description of the new forms—five new species and three new varieties—which they jointly afford.

1. All the bacilli hitherto investigated, when growing on the surface or in the depth of agar, exhibit “post-fission” movements after division.

2. Four types of post-fission movement have been noticed, which may be termed “loop-forming,” “folding,” “snapping” and “slipping.”

3. These types of post-fission movement seem to depend on the strength, adherence and mode of rupture of the capsule. In the “loop-forming” group the capsule is very strong and adherent and is very seldom ruptured. In the “folding” group the portion of the capsule uniting the adjacent bacilli in the chain is long and flexible. In the “snapping-group” the capsule seems to undergo partial rupture at the time of division, and in the “slipping” group it is completely ruptured.

4. “Loop-forming” post-fission movements are shown by B. anthracis, “folding” by B. pestis and certain organisms morphologically resembling B. anthracis, “snapping” by all diphtheroid organisms and “slipping” by organisms belonging to the typhoid-enteritidis-colon group, vibrios, the butter bacillus (Rabinowitch), B. pyocyaneus, B. fiuorescens, B. subtilis and allied organisms and many non-pathogenic species.

5. The characters of the colonies formed by organisms exhibiting loop-forming, folding and snapping post-fission movements are not markedly altered by the condition of medium under ordinary conditions of cultivation. When thickly sown on moist agar continuous growths are formed by all of them, but the edges of these growths resemble the edges of the separate colonies. All organisms exhibiting slipping post-fission movements form films on moist agar. Under unsuitable conditions for film formation the larger and stronger members produce either colonies with radiating processes on moderately moist agar, or rounded colonies on dry agar. The smaller, weaker, and slower growing members produce colonies which to the naked eye appear more or less rounded.

The following descriptions relate to a new species of Ixodes, to a new variety of Ixodes loricatus, to new species of Amblyomma and Rhipicephalus

1. Musca domestica and other non-biting flies frequenting similar feeding-grounds, are probably all liable to infection with a common flagellate. The great variability of this form is shown on comparing the flagellates in the larvae with those in the mature flies of Homalomyia, sp. and of Scatophaga lutama.

2. Infection is casual–i.e. by the mouth. In the case of the dung-flies examined, the larvae ingest faecal matter infected with herpetomonad cysts: the cysts develop into flagellates in the mid-gut, where they multiply with great rapidity: towards the close of larval life, when the larva stops feeding, they round up in the hind-gut, and are for the most part passed out as cysts. A few survive the pupal stage in a half-encysted condition, but it is probable that the infection of the adult fly is usually freshly acquired. The cycle in the fly is similar to that in the larva, and is in agreement with Patton's account of Herpetomonas muscae-domesticae. The parasite was never found in the ovaries or ova. Patton's suggestion that the degree of infection depends directly on the number of cysts ingested, is borne out by the much higher rate of infection in the larvae than in the flies: this is not surprising when we remember the complete restriction of the feeding larva to the infected area.

3. It is important to use some reliable cytological stain such as iron-haematoxylin as a control to Romanowsky stains where possible, seeing that very different results are sometimes given by the two methods.

4. The apparent double flagellum is produced in the course of longitudinal division. The new flagellum grows up alongside the old, and is not merely split off from it: this is best seen in the flagellate from the larva, where the body of the organism usually divides at an earlier period than in the fly. Study of the living flagellate is necessary to a clear understanding of the process of division.

5. I have seen no conjugation in the living herpetomonads. Occasionally flagellates were met with in Giemsa preparations devoid of a tropho-nucleus. Such individuals might be regarded as male gametes; it is more likely that they are simply degenerate forms. Sufficient consideration is not given to the possibility of degeneration in richly-nourished, rapidly multiplying protozoa, such as the trypanosomes and their allies.

6. In encystment the flagellum is not cast off bodily, but is drawn down into the cell by the kineto-nucleus, which moves to a position either alongside of, or posterior to the tropho-nucleus. In this way apparent Crithidia or even trypanosome forms are produced, but there is no hint of an undulating membrane. Small blunt “trypanosomes” were also produced occasionally by adhesion of the flagellum to the body-wall in the “stickiness” resulting from confinement under a cover-glass: the efforts of the flagellum to free itself raised up an undulating membrane, and produced a very deceptive appearance.

7. The early stages of encystment could be induced by keeping the flagellates under waxed-down cover-slips, where they would continue to live for 30—40 hours. Similar results were got by transferring flagellates to agar-agar, or by subjecting the larval host to starvation for a day or two.

8. From what I have seen, I do not agree with Chatton and Alilaire's suggestion to divide the genus Herpetomonas into Leptomonas and Herpetomonas proper. I do not think that these authors are justified in regarding the double flagellum and the presence of a long rhizoplast as generic characters.

Since the appearance of Johnston's Catalogue of the British Non-parasitical Worms in the Collection of the British Museum—a work which although not published until 1865 had been completed some ten years earlier and consequently embodies observations made more than half a century ago—the Hirudinea of the British Islands have been largely neglected. Apart from this the interest now being taken in leeches by students of their protozoan parasites and the absence of any recent work upon this group of our fauna seems sufficient apology for the revised descriptive catalogue attempted in the following pages.

Most of the specimens described in the following notes were collected by the International Fishery Commission's S.S. Huxley, in the North Sea, during the years 1905–09. They were preserved in dilute formalin in sea water, or in Bles's Fluid. Owing to the length of time during which the specimens had remained in the preservative, and in some cases owing to their large size, the fixation and preservation were not in every case as perfect as might have been wished, so that many of the finer histological details could not always be determined.

In a lecture delivered recently in Cambridge, I had occasion to demonstrate the degenerative changes undergone by P. canis and Tr. brucei in the blood of animals which had been subjected to curative treatment with drugs. These changes have not as yet been depicted. They are, in my opinion, of more than passing interest, since they may help us to distinguish normal from abnormal parasites in untreated animals. Without doubt there occurs a certain death-rate amongst blood parasites under natural conditions; what this death-rate is we do not know, but appearances which cannot be regarded otherwise than as degenerative are not infrequently encountered. On the other hand, there is always a danger that false interpretations may be placed upon abnormal or degenerative forms, and of this I fear there is ample evidence in current literature. In publishing this note I merely desire to draw attention to what may prove to be a useful method of differentiating some of the normal from the abnormal appearances presented by Haematozoa.

While examining last year some California ground squirrels, we found among this rodent's endoparasites the following protozoa, worm and mite which appear to be new. Ordinarily the mere recording of new species of the parasites of wild animals is of little interest to physicians, but since the rô1e played by O. beecheyi in the maintenance of plague on our Pacific Coast was definitely established (vide Wherry, Journ. Infect. Dis. 1908, v. 485)1 all medical men are naturally interested in the diseases which affect this rodent. Therefore the following brief descriptions of the parasites we have found are offered.

Through the kindness of Mr Nelson Annandale, Director of the Indian Museum, I have recently had the opportunity of examining a small collection of Pentastomids from that Museum. The collection contains one new species of Porocephalus and affords examples of new hosts and new localities in which species already known have been found. In all there were four different species.

The organism, commonly known under the name of the Bottle-bacillus (Flaschen-bacillus; Bacille-bouteille), was first described by Malassez (1874, pp. 203 et seq.), whose observations led him to the following conclusions (p. 211): “Il existe dans la pelade un champignon parasite. Ce champignon occupe les parties les plus superficielles de la couche cornée de l'épiderme; on le trouve entre ou à la surface des cellules épithéliales de cette couche. Il ne se rencontre qu'accidentelle-ment sur les cheveux, et encore siége-t-il sur des cellules épithéliales, qui proviennent de l'épiderme cutané. Il est uniquement constitué par des spores sphériques très-petites.

The flagellate to be described in this paper was found in the faeces of a native of the Bahamas who was admitted to the Seamen's Hospital, Albert Dock, in October, 1909. In the course of the examination of the perfectly fresh material it was noticed that numerous flagellates were swimming about. They were taken to be Trichomonas but on closer examination they were seen to differ markedly from these. In the character of their movements there was little to distinguish them from Trichomonas except that the undulating membrane so characteristic of this genus appeared to be absent. The body is pear shaped and there are three long flagella directed forwards from the blunt end of the body. By the lashing of these three flagella the animal is drawn along with the blunt end in advance and at the same time revolves upon its longitudinal axis. A very characteristic feature is the presence of a very large cytostome extending from the base of the three flagella towards the posterior end of the body for about one half to two thirds of its length. The movements of the animals were at first so violent that great difficulty was experienced in making out the details of the anatomy, but as the faeces cooled their activities began to abate. It was then seen that the flagella was as long or longer than the body and that the large cytostome was arranged in a slightly spiral manner: that is to say it did not run directly parallel to the longitudinal axis of the body.

After treatment with arsenophenylglycin the number of trypanosomes in an infected animal immediately begins to decrease, and the parasites disappear from the peripheral circulation 6—7 hours after the time of injection, the short stumpy forms being the last to degenerate.

One of the first changes noticed in the trypanosomes after treatment is the rounding up of their posterior extremities caused by the retraction of the protoplasm behind the kineto-nucleus. Meanwhile the tropho-nucleus becomes filled with granules of volutinose, which are extruded into the cytoplasm and pass along the axial filament towards the anterior extremity of the body. In dividing forms the granules form two longitudinal rows, being distributed along the two axial filaments. Finally, the granules lose their regular arrangement and become scattered throughout the cytoplasm, being more abundant, however, at the anterior end.

The kineto-vacuole, when present, enlarges considerably and may become filled with chromatic substance derived from the kineto-nucleus.

The axial filament begins to degenerate soon after treatment, often breaking up into a row of granules. Occasionally, however, chromatic substance from the kineto-nucleus passes along the axial filament, and it then appears as a thick black band extending along the middle of the cell eventually to the anterior extremity. Subsequently it breaks up into granules which dissolve in the cytoplasm of the cell.

Chromatic bodies are given off from the kineto-nucleus both before and after treatment and do not seem to be a characteristic feature of degeneration.

Sometimes the tropho-nucleus completely disappears before the cytoplasm breaks up into fragments, but at other times it preserves its form long after all other parts of the trypanosome, with the exception of the flagellum, have disappeared. These free nuclei resemble the “latent bodies” described by Salvin-Moore and Breinl, but as they, along with the fragments of cytoplasm, granules etc., are ingested by the leucocytes, it seems possible that they are merely one of the results of degeneration and not part of the life-cycle of this parasite.

These investigations have been carried on partly with the aid of a grant from the Tropical Diseases Research Fund (Colonial Office).

A good deal of doubt still exists in many quarters as to the exact meaning of the term Leucocytozoon applied to certain Haematozoa. The term Leucocytozoaire was first used by Danilewsky in writing of certain parasites he had found in the blood of birds. In a later publication he uses the term Leucocytozoon for the same parasites though he does not employ it as a true generic title. In this latter sense it was first employed by Ziemann who named the parasite of an owl Leucocytozoon danilewskyi, thus establishing this parasite the type species of the new genus Leucocytozoon. It is perhaps hardly necessary to mention that Danilewsky and Ziemann both used this name because they considered the parasite in question to inhabit a leucocyte of the bird's blood. There has arisen some doubt as to the exact nature of this host-cell. Some authorities consider it to be a very much altered red blood corpuscle, some perhaps more correctly an immature red blood corpuscle, while others adhere to the original view of Danilewsky as to its leucocytic nature. It must be clearly borne in mind that the nature of the host-cell does not in any way affect the generic name Leucocytozoon. If it could be conclusively proved that the host-cell is in every case a red blood corpuscle the name Leucocytozoon would still remain as the generic title though it would have ceased to be descriptive.

The value of arsenic in the treatment of trypanosomiasis is no new discovery.

Evans (1880), who described the first pathogenic trypanosome, recommended the administration of arsenic. Lingard (1899), for many years, investigated surra in India and treated twenty-one horses suffering from that disease with arsenious acid. One horse survived. His system of treatment was, the administration of arsenic in the form of Fowler's solution, commencing with 5 grains, twice daily and gradually increasing to 10 grains. Treatment extended over several months; the total amount of arsenic given, in some instances, amounted to over 2,000 grains. During the period of treatment intermissions of 30 to 50 days were recorded, but all the animals, with one exception, finally succumbed to the disease. Bruce (1897 and 1903), treating nagana in Zululand, gave 6 to 12 grains of arsenic in form of arsenite of soda to horses and asses suffering from that disease. Trypanosomes remained absent during the period of treatment, but reappeared immediately treatment ceased. Trélut (1907) claims to have cured cases of dourine by the daily administration of 3 to 6 grammes of arsenious acid. Archangeliky and Novikoff (1907) also record cases of dourine cured by them with arsenite of sodium and cacodylic acid. Marchal (1903) stated that he cured five stallions suffering from dourine by subcutaneous injections of 1 gramme of cacodylate of soda. Loeffler and Ruehs (1908) record a number of successful experiments on animals affected with nagana, which they treated with a solution of arsenious acid. They consider this solution to be a specific cure and a prophylactie for nagana. Laveran and Thiroux (1907–8) repeated these experiments and came to conclusions different form those of Loeffler and Ruehs.

1. Trypanosoma lewisi was found in 25% of rats caught in and about Cambridge. Of these rats 12% were young, 33% adult, and 29% old. In this region the endetnicity was localised to certain areas.

2. Fleas (C. fasciatus and C. agyrtes) were constantly found associated with wild rats infected with T. lewisi. We think that these two species of fleas are the chief carriers of the parasite from rat to rat in this region.

3. We tried transmission experiments with fleas (C. fasciatus and C. agyrtes), lice (H. spinulosus), bugs (A. lectularia), ticks (O. moubata, nymphs and adults), and Gamasus sp., but only obtained a positive result by the agency of fleas.

4. In the transmission experiments the arthropod was transferred from an infected to an uninfected animal. 16% of 138 experiments with fleas were successful, 80—98% of the fleas used were non-infective, while 2—20% were infective.

5. Distant transmission occurs with fleas. This was observed by one of us in January, 1909.

6. ‘Mechanical’ transmission occurs sometimes with fleas.

7. Infective fleas do not transmit the power of infection to their young.

8. The mechanism of infection in the case of mechanical transmission is by the bite of the flea; in the case of the distant infection it is not so.

9. The infective forms of T. lewisi for distant transmission are probably the ‘small trypanosomes’ which we have described elsewhere (1910). The forms of T. lewisi found prior to the small trypanosomes in the developmental cycle are not infective.

10. The development of the trypanosomes in the flea is not interfered with by the flea feeding on a rat immune to the disease.

11. Seventeen experiments with lice were performed, but no transmission was obtained by their agency. 1139 lice were used. No confirmation of Baldrey's infective cycle in lice could be obtained.

12. We could trace no connection between transmission of infection by lice and the presence in them of ‘developmental forms.’

13. No transmission of T. lewisi by other arthropods was obtained. These negative results had no connection with the presence in the arthropods of ‘developmental forms.’

In conclusion we would like to thank Professor Nuttall for his kindness in inoculating our animals and providing us with the material for our experiments, and for his interest and advice in our work.

The internal organisation of the Ceatoda is described as follows by Sedgwick (1898, p. 246):

“Beneath the cuticle-like outer membrane is a layer of spindle-shaped cells lying at right angles to the surface; their external ends abut upon the cuticle, and their inner ends are prolonged as fibres into the parenchyma. Beneath this layer there is a delicate superficial layer of longitudinal muscular fibres, and next a parenchyma of connective tissue in which strongly-developed bundles of longitudinal muscular fibres, as well as an inner layer of circular muscles, are embedded; both these muscular layers are traversed, principally at the sides of the body, by groups of dorso-ventral muscular fibres.”

In a previous paper which appeared in Parasitology, Vol. III. pp. 73–07, and the Journal of Tropical Veterinary Science, Vol. n. No. I, details were given of thirty-two cases of successful treatment of Surra in horses by means of arsenic and its derivatives.