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.

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

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.

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).

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 three forms of Trypanosoma gambiense have been described so often that a few words of apology are needed before brining forward the follwing note on the subject.

The development of T. lewisi in the blood of the rat is accompanied by a division of the nucleus which is more like an amitosis than a mitosis.

The division of the blepharoplast, always preceded by the division of a karyosome-like granule, might be called a promitosis (sensu: Nägler, 1909).

It is not proved that autogamy or parthenogenesis takes place in rats' blood or in cultures. The evidence brought forward by Prowazek and by Moore, Breinl and Hindle proves only the existence of chromidia; neither are Schilling's recent proofs suggestive.

Under abnormal conditions hypertrophy takes place affecting the nucleus and the blepharoplast, with subsequent formation of chromidia and final fragmentation. Similar stages found in the rat-louse have been described as sexual cells.

Considering these results in connection with previous observations of Strickland and myself, we may conclude that as yet nothing whatever indicates the occurrence of any sexual process in the life-cycle of T. levrisi, both in the vertebrate and invertebrate hosts.

The fact that no inquiry seems to have been made into a matter of some general interest, namely, the reasons which, apart from “hunger,” induce mosquitoes to bite, may serve as an excuse for presenting the preliminary results of an investigation which has had, for the time being, to be discontinued. The following observations on mosquitoes were made at the Pusa Research Institute.

The collection and study of tropical insects now heing undertaken in connection with medical and other researches has resulted in the publication of two or three very useful leaflets of instructions as to how to catch and send home specimens of blood-sucking and parasitic insects. These leaflets are intended for collectors who will send home their specimens soon after they have caught them: when this is impossible, when specimens have to be carted from place to place and housed, it may be, in very unsuitable quarters, it becomes important to use only the best methods for preserving them in good condition, and the best methods can be arrived at only by combining the experience of collectors in different countries.