The history of the ticks (Rhipicephalus appendiculatus) employed for transmission of East Coast fever is detailed in Part I. During the 1st day the ticks generally become attached and are partly held in place by a kind of cement substance (Fig. 1).

Penetration usually occurs at some time during the 2nd day, and the cellular elements of the corium quickly respond. There is a local swelling of the capillary endothelium, an infiltration with polymorphonuclear leucocytes and a slight increase in eosinophiles. More cement substance is produced which hardens about the edges. Some of it enters through the wound and spreads out in the corium along lines of least resistance (Fig. 2).

Later on the eosinophiles increase greatly in number and in turn give place to macrophages which ingest some of the cement substance. Mast cells also become more numerous. The area of reaction extends 2 or 3 mm. from the tip of the proboscis. Marked cytolysis of fibroblasts, of histiocytes and of the swollen endothelial cells occurs. The latter leads to haemorrhage (Figs. 6, 8, 9). The red blood cells and leucocytes are, however, not destroyed. They are sucked up by the tick, the leucocytes first because they accumulate before the haemorrhages take place.

Twenty-five of the sixty-six ticks examined were found to contain parasites in their salivary glands, but no parasites were seen in the sixty-six pieces of skin excised while the ticks were attached. Soon after the parasites enter the blood stream and spread throughout the system the corium of the skin is invaded by them like other parts of the body (Table III).

The medium-sized lymphocytes are the principal cells parasitised; but parasites are also found in lymphoblasts, large and small lymphocytes and occasionally in parenchymatous liver cells. We never saw them in vascular endotheial cells. For this reason we are unable to substantiate the view, which has apparently never been seriously questioned, that they undergo schizogony in this situation. The first agamonts were noted in lymphocytes in gland smears the day the fever first exceeded 103° F. The gamonts appeared about a day later and the intra-erythrocytic forms soon after. Taking the average of a number of cases: (1) The temperature first surpassed 103° F. on the 9·8th day after infestation with ticks. (2) The first Koch bodies within lymphocytes were observed on the 14·8th day, that is to say, 5 days after the fever commenced. (3) The first parasites within the red cells were noted 1·6 days later, on the 16·4th day after infestation.

The cycle which the parasite undergoes in changing from the agamonts to the intra-erythrocytic forms is illustrated in Diagram II (fully described on p. 36).

The alterations in the tissues caused directly or indirectly by the parasitic invasion were studied principally in specimens secured at autopsy from animals killed in extremis. The changes which apparently dominate relate to the lymphatic system. The medium-sized lymphocytes and to a less extent the small and large lymphocytes and lymphoblasts, first in the lymph glands and later in all parts of the body, become infested with Koch bodies which grow in their interior apparently without causing any severe injury. The distribu tion of Koch bodies is recorded in Table III, and their incidence in the lymph glands and in the liver in Tables IV and V. The evidence presented does not support the current conception that the parasites serve as a powerful stimulus to the multiplication of lymphocytes. The enlargement of lymph glands is caused more by oedema than by increase in their number. But there is a marked redistribution of lymphocytes. Their number is reduced in the lymph glands and in the peripheral blood stream and increased in the blood vessels of the liver and some other organs. Perivascular lymphocytic infiltrations are also a notable feature of the reaction in the liver, kidneys, adrenals and several other organs, but they are of rare occurrence in the nervous system. It is uncertain how far they are formed by the emigration of lymphocytes from the blood stream and by the proliferation of lymphocytes previously present perivascularly.

Small haemorrhages constitute a second alteration of importance. They are particularly prone to occur in the epicardium and endocardium, but may be found in almost any part of the body. Evidence is lacking that these haemorrhages play a part in the genesis of the perivasoular lymphocytic infiltrations. The latter are far more widespread and are chiefly observed in locations where haemorrhages are seldom seen.

Oedema is a third type of reaction. It is constantly found in the lymph glands and occasionally in the lungs, especially in the later stages of the disease.

Generally speaking, therefore, the lesions reported in this paper are acute in type. The functional activity of the several organs (except the lymph glands) has not been impaired sufficiently severely or over a time long enough to leave distinct structural changes in the parenchymatous organs; but the specimens examined were not collected from protracted cases of East Coast fever or from animals under suspicion of having undergone repeated attacks of the disease.

It is the parasites in the red blood cells which are capable of continuing the cycle if they are ingested by ticks able to act as vectors. We have recog nised three principal groups: (1) small spherical-ovoid parasites which are the first to make their appearance, (2) tailed parasites, and (3) plunip forms, both of which develop later and become more numerous than the spherical-ovoid parasites. Possible stages of transition are represented in Diagram I (p. 37). Though many parasites undergo differentiation and some probably divide, a variable number degenerate within the erythrocytes.

We question the validity of the genera into which the family Theileriidae are customarily divided on account of the inadequacy of the data on which they are based.

1. Two new schizogregarines are described from the gut of the polychaete worm Potamilla reniformis (O.F.M.). One of these is meanwhile retained in the genus Selenidium Giard as S. potamillae n.sp. For the other a new genus, Meroselenidium, is proposed, of which M. keilini is the type species. The life cycle has been followed in both gregarines.

2. The schizogony of Meroselenidium is characterised by the formation of cytomeres preliminary to the liberation of merozoites. In Selenidium potamillae the schizogony is more like that in S. mesnili and S. caulleryi, though there is a considerable residual body.

3. The gametocytes become attached by their posterior ends. In S. potamillae there is often a multiple association. The gamete nuclei are formed within the nuclear area of the gametocytes. Further development takes place in sea water. Isogametes have been observed in S. potamillae.

4.The gametocyst of Meroselenidium keilini is elliptical in outline and measures about 70 × 55μ. It contains some twenty relatively large spores, 27 × 15μ, the walls of which are transversely ridged; the spores are polyzoic. The gametocyst of S. potamillae is of much the same shape, but only about half the size. The sporocysts are very numerous, spherical, smooth-walled, and measure about 8·5μ in diameter. In neither species does the gametocyst contain any residual mass.

We take this opportunity of thanking the High Commissioner of India and the Delegacy of King's College for grants-in-aid received by one of us (H. N. R.) during the course of these investigations.

1. An account is given of Aproctonema entomophagum Keilin 1917, a Nematode parasite of the larvae of a Mycetophilid fly, Sciara pullula Winn., inhabiting decaying wood.

2. The life history of this parasite is remarkable in the following respects:

(a) The free-living stage is very short.

(b) Both sexes are parasitic.

(c) The usual host is the larva of the fly, from which the parasite escapes by actively breaking through the skin; but some parasites may be carried through to the imagines, from which they escape largely by the aid of the egg-laying movements provoked by them in the flies.

3. Metamorphosis of the Sciara larva is delayed by the parasitism, so that at least two generations of Nematodes may be found in one host.

4. All the parasitised imagines so far examined have been females.

5. The systematic position of Aproctonema is discussed, the conclusion being that this worm and its near relative, Tetradonema plicans Cobb 1919, represent two closely allied genera of the family Mermithidae, but are not synonymous with Mermis. It is proposed to dispense with the family Tetra-donematidae Cobb.

1. The results of previous workers on the action of plasmoquine on avian malaria, Plasmodium relictum (Grassi and Feletti, 1891), have been confirmed and extended. Sterilisation was obtained in a large proportion of birds (16 out of 33) treated during the normal incubation period.

2. Thirteen new synthetic quinoline compounds were found to have antimalarial action.

3. Two of these compounds, R 25 = 8-γ-aminopropylamino-6-ethoxy-quinoline and R 36 = 8-γ-anunopropylamino-6-methoxyquinoline, have therapeutic indices of 1: 16, are nearly equal to plasmoquine in potency and resemble it in action.

4. A third compound, R 44 = 8-γ-aminopropylamino-6-n-butoxyquino-line, has a therapeutic index of only 1 : 8, but its sterilising action is equal to or greater than plasmoquine, R 25 and R 36.

5. The remaining compounds have therapeutic indices of 1 : 8 or 1 : 4 and vary in their sterilising action.

6. Experiments are described which show the formation of methaemo-globin in vitro through the action of plasmoquine, R 25 and R 36. In this respect the order of activity of the compounds is R 36, R 25, plasmoquine.

1. The results of further tests with the red-cell adhesion phenomenon in trypanosomiasis of man and other animals, described first by Duke and Wallace (1930) and later by Wallace and Wormall (1931), are discussed.

2. The conclusion is reached that the tests should always be made with several different strains of trypanosomes; in this way the number of negative results with undoubted cases of trypanosomiasis is decreased considerably. It is also advisable to have available stock adhesin sera (human or monkey) so that preliminary tests can be made to determine whether the trypanosomes in any animal are capable of giving adhesion. In doubtful cases of trypanosomiasis, treatment with trypanocidal drugs should be started. This treatment usually results in a marked improvement in the power of the serum or plasma of men and monkeys infected with trypanosomes to give red-cell adhesion.

3. If a suitable small amount of phenol is added to the serum of a trypanosomiasis patient, this serum can be kept at the ordinary temperatures for 3 weeks or more without appreciable loss of its power to give red-cell adhesion. In this way it is possible to carry out tests at a central laboratory on sera which have been collected at outlying stations.

4. Experiments have been carried out to determine the amounts of adhesin and complement (or “X factor”) required for red-cell adhesion.

5. The adhesin is non-dialysable, and in this, and many other respects it behaves like a true immune body.

A Previous paper (Bishop, 1932) dealt with the cultivation of a Hexamita sp. found in the horse-leech (Haemopis sanguisugae = Aulastomum gulo). The present paper deals with the morphology and method of division of the Hexamita above referred to, which I now name H. gigas n.sp. Dobell (1909) gave a detailed history of the nomenclature of the genus, and Wenyon (1926) has dealt with the same subject and given a list of the then known species and their hosts. Two species have since been described: H. pulcher, by Becker (1926), from the caecum of the ground squirrel Citellus tridecemlineatus, and Octomitus (= Hexamita) pitheci described and figured by da Cunha and Muniz (1928) from the intestine of Macacus rhesus. Apart from the two species (Hexamita nodulosa and H. inflate) described by Dujardin (1841) from stagnant water, and in which he saw but six flagella, a single species only has been described hitherto from a non-vertebrate host. This species, Octomitus (= Hexamita) periplanetae, a small flagellate 5–8 μ in length, from the gut of the cockroach, was described by Bělař (1916); a similar flagellate from the gut of Blatta orientalis has been found by me.

The different types of malaria pigment occurring in oocysts of naturally infected Anopheles caught in human dwellings at Kampala, Uganda, are described and figured (selection from 204 camera lucida drawings).

The exact significance of each particular type of pigment is uncertain and in the present state of our knowledge it is not possible to do more than to place them tentatively into four groups and to indicate to which species they probably belong.

1. Accurate measurements were made of adults, larvae and eggs of Rhabditis pellio, representing an average selection for comparison with Johnson's figures.

2. The most satisfactory method of culturing the nematodes was in hanging drops, in a medium free from an excess of putrefying bacteria.

3. A medium poor in food was found to prolong life (up to 40 days), while a rich medium quickened up the life processes thereby causing death sooner. It is probably partial starvation which prevents the larvae from becoming mature while in the living earthworm.

4. In a medium favourable for prolonging life, the males were found to live about one-third as long as the females (F generation). It is probable that the females only live for about 4–8 days in a decaying earthworm after attaining maturity.

5. The maximum number of eggs laid per female was 257 (F generation) and 197 (F1 generation). It is probable that between 150 and 300 eggs are laid per female in the natural state. No information was obtained regarding the effect of the various media on egg production.

6. In most cases the females died when spent of eggs.

7. Vivipary is considered to be due to a favourable environment probably aided by a high temperature.

8. Larvae were found to be more susceptible to cultural conditions than the adults, especially those (F generation) which were not bred from females in culture media. The growth-rate of F1 generation larvae was found to be slightly faster in a natural medium, such as earthworm broth, than in peptone.

9. The chief food is considered to be bacteria.

10. During this work R. pellio behaved entirely as a bisexual species. A few cases of copulation were observed, showing that some of the males had not lost their “sexual instinct.”

11. Rhabditis pellio is considered to be a species in which hermaphroditism is just commencing and in which true males and females exist together with hermaphrodite females whose numbers fluctuate, the degree of hermaphroditism possibly bearing some relation to the sex ratio.

12. The sex ratio was about 1 ♂: 2 ♀♀, in both the F and F1 generations, but varied considerably. There were a few cases in which the male proportion was equal, or higher, than the female.

13. Four different species of British earthworms were examined, each being infected by Rhabditis pellio to a varying extent. Eisenia foetida was, however, rarely infected. Size of the earthworm, in proportion, played no part regarding the degree of infection. There is an indication that the head (segment I to the beginning of the clytellum) is the most heavily infected region.

14. A few specimens (larval stage) of an Ascarid, a species of Porrocaecum, a parasite of small mammals and birds, were found in three of the species of earthworms examined.

15. A probable course of the life history is given, based on this work and that of Johnson (1913).

Through the kindness of Dr S. W. Kemp, F.R.S., and of the Discovery Committee, the writer has recently had the opportunity of examining examples of a species of Uncinaria from the intestine of a sea-lion. These were collected by Mr J. E. Hamilton, of the Discovery staff, at Cape Dolphin in the Falkland Islands, in April 1931. The host was a sea-lion pup, about three months old, which was found dead on the beach, and it was suspected that the worms were concerned in the causation of its death.

Amoebae of the genus Endolimax have been found naturally inhabiting the large intestine of 3 species of Macacus (M. sinicus [= radiatus], M. rhesus [= mulatto], M. nemestrinus).

In all these hosts the amoebae are morphologically and culturally identical, at all stages of development, and are indistinguishable by any structural or cultural character from Endolimax nana of Man—with which they have been carefully compared. The several forms have been studied in “pure” culture (i.e., free from all other protozoa, but accompanied by bacteria suitable for their growth).

The Endolimax of M. sinicus, isolated in “pure” culture, has been experimentally transmitted to an uninfected man by the natural route (cysts per os): and in this human subject it has produced an infection indistinguishable from a natural one with E. nana. The induced infection has now persisted unchanged for close on 8 years.

From the experimentally infected man the amoeba has been artificially transmitted to an uninfected M. rhesus, in which it gave rise to an infection—likewise indistinguishable from a natural simian infection—which persisted for the rest of the monkey's life (2½ years).

Some further information is given about the distribution, cultivation, emetine-resistance, and other peculiarities of the forms of Endolimax found in Macaques and Man; and the findings of other workers with similar organisms are briefly considered. From all the evidence available it is concluded that E. nana naturally lives not only in Man but also in at least 3 different species of Macacus, and probably in monkeys of this genus generally. As yet there is no evidence that more than one species of Endolimax inhabits any of these hosts.

Infections with E. nana, whether in Man or Macaques, have usually been found to endure indefinitely; but a case (M. rhesus) has been observed in which the infection appears to have died out spontaneously after persisting for a known period of over 6 years.

Attempts to infect kittens with E. nana have all been unsuccessful hitherto, but there is evidence (from the work of others) that this amoeba may inhabit some other domestic mammals. Its host-distribution in nature needs further investigation.

For many years it has been known that the domestic fowl, together with some other species of birds, is susceptible to experimental infection by trypanosomes of the brucei group. The successful experiments were performed in European laboratories with strains whose virulence had been greatly exalted as the result of long maintenance in small laboratory animals. Infection was induced by inoculation of infected blood into the comb, the peritoneum or a vein. A natural infection of birds with these trypanosomes has, as far as I know, never yet been reported.

The prophylaxis of plasmodial infections, by means of drugs in general, and by plasmoquine in particular, has been the subject of two reports to which we wish to refer: (1) by James, Nicol and Shute (1931), and (2) by Swellengrebel and de Buck (1931). The authors of report (1) obtained complete success by the use of 0·06 g. of plasmoquine before, and daily for 6 days after, the bite of infected mosquitoes, while the authors of report (2), giving 0·03 g. of the drug daily, had but poor success, notwithstanding Ottolenghi and Brotzu (1929), whom they cite, having reported that 0·02 g. daily with 0·25 g. of quinine was a good practical prophylactic.

The parasitic nematodes described in this paper were collected by Dr E. C. Faust during his stay in China, and sent to Prof. Hoeppli for identification and study. The total collection amounts to about 500 vials, the majority of which were collected in Peiping (Peking), mainly from birds.

In 1922 J. W. W. Stephens the morphological characters of the asexual forms of a malaria parasite which he had studied in the blood of a patient from East Africa were different from those of any usually accepted species, and he proposed to establish the parasite as a new species with the name Plasmodium ovale. In 1927, in collaboration with D. U. Owen, he confirmed and extended the description from the study of a case infected in Nigeria. In 1930 Warrington Yorke and D. U. Owen studied another case from Nigeria and, by utilising this patient's blood in the practice of malariatherapy, they were able to show that the peculiar morphological features of the asexual stages of the parasite remain constant when it is passed from person to person by direct blood inoculation.

1. The life history of Lecithodendrium chilostomum has been established; C. Lecithodendrii chilostomi penetrates a second intermediate host, the larva of Phryganea grandis, and unlike other stylet cercariae does not encyst, but feeds and grows in the host tissue as a mobile metacercaria. During pupation of the host in the following year these mobile forms migrate from the abdominal segments of the larva to the thorax, where they then encyst in the thoracic muscles in which they are also found in the imago. The largest metacercariae and the excysted worms are typical early adult Lecithodendrium chilostomum. No case of progenesis in the metacercaria was found.

2. It is estimated that the maximum swarming of the cercariae probably occurs during July, when first penetration of the intermediate host takes place. Subsequent diminished swarming and penetration proceed until November. The life of the larval trematode as a mobile metacercaria is approximately 8 months; the imagines of Phryganea grandis emerge during May and June, the infective period for the final host.

3. The metacercariae are not distributed throughout the body cavity of their larval host, but the majority are confined to the three posterior segments.

4. Limnophilus rhombicus may also serve as a second intermediate host, but the infection is very light and the metacercariae do not encyst during pupation of this host.

5. The excretory system has been determined in all stages of Lecithodendrium chilostomum; it is of the 2 (6 × 2) type. The occurrence of this type of system in other groups of cercariae is reviewed and since it is found in several widely separated families, it is suggested that its presence does not necessarily imply relationship, but is due to convergence.

6. The life histories of the following bat trematodes are indicated: Lecitho-dendrium lagena, Plagiorchis vespertilionis and Crepidostomum moeticus.

7. The life history of Dicrocoelium dendriticum is discussed.

Extraordinary as any of the Mallophaga are when compared with conventional insect forms, there are some species of the order which are still more peculiar than the majority of their fellows. Among these unusually strange forms is that here to be dealt with, a species that seems to combine within itself the characteristics of two otherwise trenchantly separated groups, that possesses striking specific peculiarities and that in addition is decidedly aberrant in its choice of host. It has but once been recorded. The availability of further specimens makes possible additions to our knowledge of its structure and a reconsideration of its relationships.

On the skin of the dorsal surface, and particularly on the dorsal fins of Scyllium canicula at Plymouth, occurs a parasite which appears to be identical with Paracotyle caniculae Johnstone 1911. In British waters it was first noticed by Scott (1906) who queried it as a species of Epibdella. Johnstone (1911) gave an account of the species but his specimens were immature, being in the male phase of their development and considerably smaller than those found at Plymouth.

In most parts of the world helminth infestations are responsible for such a heavy wastage of sheep that their control has undoubtedly become one of the most important charges that devolve upon the flock-owner. It might be thought that in tropical regions suited to the raising of sheep the problem of helminth control would cease to be urgent; and that climatic conditions, the general aridity of land chosen in such countries for sheep-rearing, and its consequently smaller carrying capacity, would contribute to form an environment distinctly unfavourable both to the survival of the free-living stages of parasitic worms and to their chances of reaching a suitable intermediary or definitive host. Such areas are not usually well watered, and it certainly does result from the paucity of permanent streams and standing water that few species of trematodes are represented. Those species that do occur, e.g. Fasciola hepatica, F. gigantica, are restricted to particular localities and are easily subjected to control.

The experiments described show that plasmoquine is very effective in preventing or delaying attacks of malaria in birds infected with P. relictum by direct blood inoculation, but has little or no prophylactic action in birds infected by the bites of mosquitoes.

In the mosquito-induced malaria parasites may appear in the blood 3 or 4 days after the cessation of plasmoquine treatment and there is no appreciable delay as compared with untreated control birds.

Les collections de l'lnstitut Pasteur possèdent un assez grand nombre d'exemplaires, à tous les stades, d'un curieux Argasiné recueilli en 1911 par la mission Bouet-Roubaud, au cours de son exploration parasitologique des régions soudanaises de I'Afrique Occidentale française. Cet Acarien avait été rencontré par G. Bouet à, Djenné, dans des trous d'arbres ou des cases obscures servant de refuges à plusieurs espèces de chauve-souris: Hipposiderus tridens Et. Geoff., Taphozoüs perforatum Geoff., cette dernière espèce parasitée par un trypanosome.