In 1915 Dowden reported a suspected case of tsutsugamushi disease, or Japanese river fever, from the Federated Malay States. Twelve years later Fletcher and Field (1927) were able to examine a series of cases and established Allothrombium. This spelling is adopted by Oudemans. In the absence of definite evidence of the original derivation, it would appear, in the light of Opinion 34 of the Rules, that the original spelling should be preserved, and Trombicula is therefore used in this paper.

1. In addition to the parasite of East Coast fever three other organisms were observed. The first of these is a “symbiont” and was found in the Malpighian tubules and ovaries of all the ticks examined; the second, a protozoan, was observed in about 50 per cent. of our ticks in the process of multiplication in the epithelial cells of the gut and in the large phagocytic cells of the body cavity; the third, from its very active movements, probably a ciliate, was seen only in dark field preparations of a few ticks recently engorged. Once recognised these organisms were always easily distinguished from Theileria parva. We were unable to confirm the assumption of Nuttall and Hindle (1913) that practically 100 per cent of ticks fed on blood containing parasites become infective and are thus capable of transmitting the disease. Approximately accurate figures on the survival of ingested parasites can only be secured from sections. Of the 290 ticks of our standard series examined in very complete serial sections, parasites were found in 178, or 60·1 per cent. In the first series of infective nymphae, in which we kept records of sex, 33 per cent. of the ticks containing parasites were females and 66 per cent. were males.

2. In the erythrocytes of the animals suffering from East Coast fever on which the ticks engorged large and small parasites were distinguishable (Figs. 29 and 30 and Fig. I, p. 32). Both showed signs of division.

3. Intra-erythrocytic parasites were observed in the gut of the ticks only up to the sixth day after engorgement (Table V). Liberation of parasites takes place at a different rate in different ticks.

4. Parasites were seen free in the lumen of the gut from the time of engorgement up to 10,13,14 and 8 days, as indicated in Tables I–IV. Beginning about 2 days after engorgement and until they disappear from the gut there is a marked tendency for the parasites to be arranged in clumps, the small ones together and the large ones together (see Fig. I at 2). But the small and large parasites are sometimes scattered indiscriminately. Both types tend to accumulate on the surfaces of the epithelial cells lining the gut (Fig. I at 3).

5. Many parasites are taken up by epithelial cells which stretch further into the lumen than their neighbours and are called “pedunculated.” They are accompanied by lymphocytes, leucocytes, platelets and a variety of foreign materials. Parasites were observed in this situation from engorgement to 14 days (Table I), from the second to thirteenth day after engorgement (Table II), from the sixth to the twenty-first day after engorgement (Table III), and from the first to the eighth day after engorgement (Table IV). The examinations listed in Table III began on the sixth day. The fact that parasites were not seen earlier in this series in the pedunculated cells does not mean that they were absent. On each day during these rather long periods large and small parasites were observed which stained brilliantly and some of which appeared to be dividing. Other individuals of both types stained but feebly and from their irregular outlines were clearly degenerating. How long individual parasites remained could not be determined. Table I shows their presence in pedunculated epithelial cells 4 days after disappearance from the lumen, and Table III, 5 days after. But in the ticks recorded in Tables II and IV they disappeared from the pedunculated cells on the same day that they could no longer be seen in the lumen.

6. It is the parasites which enter non-pedunculated epithelial cells which carry on the life cycle. They enter in smaller numbers and more slowly. Tables I, II and IV record their appearance in this commoner type of epithelial cells just 7 days after they were first noted in the pedunculated cells. They remain intra-epithelial for as long as 20 days (Table I), 25 days (Table II), 22 days (Table III), and 16 days (Table IV). As a rule they are not accompanied by leucocytes and different sorts of debris. The small forms soon disappear. Large forms like those seen in the lumen are at first present in considerable numbers and give rise to a parasite distinctly different from any previously seen, which we call a “zygote,” although we have been unable to demonstrate the process of fertilisation. These zygotes have rather irregular outlines, stain blue by Giemsa's method and are for a time without red-staining nuclei. In this condition they are represented in Figs. 1–5, 40 and 41 (a–d); also in Fig. I at 4 and 5. In this phase of the zygote the parasites have to resist the digestive action of the cell containing them and many succumb, but some grow; their diameter increasing 300 or 400 per cent. (compare Figs. 1 and 5).

The surviving ones begin to exhibit once more characteristically red-staining nuclei about 18 days after engorgement and at approximately the time of moulting (Figs. 6, 41, e–h). Coincident with this change their outlines become smooth and they are evidently less susceptible to digestion. Oökinetes develop very rapidly within their interior (Figs. 42–49 and Fig. I at 6). All stages in the formation of oökinetes from blue-staining zygotes to others which are fully differentiated and have escaped from the epithelial cells of the gut into the body cavity are frequently seen in a single tick. Oökinetes were observed from the first to the eighth day after moulting in sections and to the ninth day in smears (Table II), from the first day before moulting to the eleventh day after (Table III), and from the second day before to the ninth day after (Table IV). They are illustrated in Figs. 7, 11–14 and 49.

7. The oökinetes begin to enter the salivary glands about the time of moulting. Our failure to detect them in this situation in our larval series (Table I) until 11 days after moulting is a negative observation, possibly due to technical difficulties, and of little significance compared with their definite discovery in the salivary glands 1 day after moulting (Table II), 1 day before moulting (Table III), and 1 day after moulting (Table IV). But this entry is probably not restricted to the days mentioned, for typical ookinetes were observed 9 days (Table II), 12 days (Table III) and 10 days (Table IV) after they were first noted in the salivary glands. It is therefore probable that successive crops of oökinetes enter the salivary glands over a relatively long period and that this explains the discovery of parasites in different stages of development in the salivary glands of individual ticks. Soon after penetration they round up but can be recognised at least until 5 days after moulting by their intensely blue-staining cytoplasm and red-staining nuclei (Figs. 15, 50, 51).

The next stage, which we refer to as a beginning “sporont,” is represented in Figs. 16, 52, 54 and to the right in Fig. I at 8. The nucleus of the oökinete is lost, but the parasite can be identified within the salivary gland cells by its intense deep blue colour when stained by Giemsa's method, by the clear halo about it, and by its relatively large size. The salivary gland cell containing it is usually considerably distended. This condition persists for a variable time which we estimate at about 3 days. Approximately 8 days after moulting buds appear on the surface of the sporont (Figs. 17 and 53) and spherical masses within its interior (Fig. 55) which constitute the “sporoblasts.” At the same time the central part of the parasite stains less intensely and the halo about it becomes barely distinguishable (Fig. I at 10). A little later on the central part stains still less strongly and the sporoblasts become proportionally more clearly defined (Fig. 18). Red-staining chromatin reappears in irregular masses in the sporoblasts (Fig. I at 11). This, in our experience, is as far as the parasite develops before the ticks containing it are placed on animals with a view to transmitting East Coast fever. During the first 3 days of feeding on susceptible animals the parasites were examined in great detail.

After 1 day a total of ten ticks were studied in serial sections, of which three contained parasites in their salivary glands. All of them were in the sporont stage. The central area of the sporont shown in Fig. 19 is developed beyond the condition illustrated in Fig. 18. It is less dense, it is stained a light bluish green and the sporoblasts have moved from it to the periphery. A careful search was made of the digestive tracts of all three ticks. No blood cells could be detected. The lumina were not sufficiently dilated to suggest the intake of cell-free plasma or lymph.

After 2 days four out of ten ticks examined contained parasites. In three of them sporonts were observed which apparently did not differ from those just described; but in the fourth (an adult female) the sporoblasts were further separated from the parent mass—a change which seemed to be preliminary to the more radical development noted the next day. In this particular tick no blood cells could be detected in the lumen of the digestive tract, which, however, was slightly but distinctly dilated perhaps by fluid from the animal on which the tick fed.

After 3 days a striking alteration occurred in the organisms in all five of nine ticks parasitised as illustrated in Figs. 57 and 58. The red-stained chromatin represented in Fig. 57 which before (Fig. 56) was distributed irregularly is becoming arranged in small masses at the surfaces of the sporoblasts. The differentiation of these chromatin masses is still further advanced in Fig. 58, though it illustrates conditions in the same tick. The masses have in many cases broken loose from the sporoblasts, and each is seen to be made up of some blue-stained cytoplasm in which a single spherical or cup-shaped nucleus is embedded. These are the sporozoites. While this development of sporozoites in association with the sporoblasts was observed in all of the five ticks wellformed sporonts like those illustrated in Figs. 18 and 19 were only seen in one. All of the ticks seemed to contain a slightly increased amount of fluid in their digestive tracts, but in only one could ingested leucocytes be recognised.

The period from 4 to 18 days is divisible into two parts: before engorgement (Figs. 20–25, 60–67) and after engorgement (Figs. 26–28, 68, 69).

Before engorgement the maximum production of sporozoites takes place. At 4 days the process is going on with extreme rapidity. Figs. 66 and 67 show two active sporoblasts with sporozoites radially arranged about their periphery. The morphology of the sporozoites on the fifth day is well shown in Fig. 59. When first formed they are somewhat larger than when later on they are ready for discharge. This difference is illustrated in Fig. 23 and in Fig. I (compare stages 12 and 13).

At 5 days larger sporoblasts were noted (Figs. 60–65), and the sporonts are broken up by the spreading apart of the sporoblasts through the tremendous development of sporozoites (Figs. 20–22). Fig. 24 represents a mass of sporozoites apparently ready for discharge into the lumen of the acinus on the right.

The maximum number of salivary gland cells in any tick containing parasites at any stage in the cycle is about 50 per cent. Such an infestation is, however, very exceptional, occurring in only four or five of the fifty-nine ticks of our standard series possessing parasites in this location. The usual infestation is about 8 per cent. In some ticks, however, parasites are only to be found in one or two cells after long search; that is to say, in a percentage of, say, 0·1 per cent. But when the infestation is so small the individual cells involved may be charged with parasites just as heavily. By far the heaviest cellular charge with parasites, though not the highest percentage infestation, was discovered in five out of seventeen female ticks found naturally attached to an animal in a region in which East Coast fever was very common. The degree of infestation probably depends upon the number of ookinetes which settle in the salivary glands and the individual cellular charge upon adverse or favourable conditions in the salivary glands to the development of parasites.

After engorgement both the percentage infestation and the cellular charge are apparently reduced. The conditions 6, 8, and 11 days after attachment are illustrated in Figs. 27, 28 and 68 and 69. Many of the parasites are obviously degenerating, and the whole mass of parasites may be sloughed off from the cell into the lumen of the acinus (Fig. 29). The last parasites were seen 18 days after the tick containing them was placed on a susceptible animal (Table IV), which is long past the time of probable transmission of the disease. Our experiments do not show how much longer they persist and it is likely that they are soon destroyed, because it has been proved experimentally by other investigators that the ticks are cleansed by feeding.

8. Three of our four series of ticks, which contained parasites in their salivary glands, which were fed on susceptible animals, produced typical cases of East Coast fever. It is probable that the other series (Table II), which possessed parasites in equal abundance, would also have transmitted the disease if the animal infested had not died so soon under chloroform anaesthesia as we were removing a lymph gland for study.

The structure of the head and especially of the mouth-parts of these economically very important flies has been studied by many observers. The first very brief remarks on the proboscis were made by Wiedemann (1830), in his original description of the genus Glossina. He pointed out that the proboscis is almost as long as the thorax, and setiform and triangular in its basal part, the palps almost as long as the proboscis and horizontal. In the same year, Robineau-Desvoidy (1830) described another species of tsetse-fly, Glossina palpalis, but under the generic name Nemorphina, which became a synonym of Glossina. In his diagnosis of the genus, he gave an even shorter description of the proboscis which he believed was not adapted for sucking blood.

1. Six species of Amitermes, one from Panama and five from California, have been examined for protozoa. Certain protozoa have been found in many or all individuals examined of all species, but they are much less abundant than are flagellates in termites of the three xylophagous families below the Termitidae.

2. Trichomonas lighti n.sp. has been found in all species, but not in all individuals.

3. Chilomastix minuta n.sp. occurs in Amitermes beaumonti.

4. Embadomonas termitis n.sp. is described from Amitermes beaumonti.

5. Endamoeba beaumonti n.sp. has been observed in five host species. In its size and nuclear structure it resembles Endamoeba disparata of Mirotermes hispaniolae.

6. Nyctotherus silvestrianus n.sp. has been found in three of the Californian species. It resembles N. termitis and N. ovalis, but is larger than the former and smaller than the latter. A long filament is attached to the end of the cytopharynx. A thickened, V-shaped structure lies against the cyto-pharynx. Several deeply staining fibrils arise from this V.

7. A coccidian has been found in one individual of Amitermes minimus. This forms sixteen banana-formed merozoites and three sporoblasts as in Chagasella.

8. Micro-organisms other than protozoa are very abundant in the intestines of all six species of Amitermes, and they are similar in all.

Kenya Colony offers a rich field for the study of ticks and tick-borne diseases. The natural conditions under which both ticks and the diseases exist range from those of the hot, low-lying coastal lands to the equable climate of the highlands culminating in the colder upland country and mountain slopes. The variety of conditions is also attributable to the extensive tracts of bush-covered country, the high plateaux with their scanty growth of vegetation, and to the forest-clad ridges and mountains.

It is often desirable that a mid-gut showing oocysts be preserved for demonstration purposes or for record. The method herein described seems to have certain advantages over those usually recommended in saving considerable time during fixation, staining and mounting of the specimen, also in permitting pigment within oocysts being seen on any part of the mid-gut. The stain used (toluidine blue) is not taken up to any great extent by the nuclei of the gut cells, but appears to have some degree of selective action on the younger oocysts.

Although much work has already been published on the bucco-pharyngeal mechanism of a blow-fly larva, a close examination reveals the presence of parts hitherto overlooked or but imperfectly recorded. In this account current nomenclature is retained as far as possible; but where the evidence warrants it new terms are employed based on homology, or on the function of the regions concerned, in an endeavour to arrive at a more useful basis for future reference.

The 60th Union Helminthological Expedition (Skrjabin, Podjapolskaja and Schulz, 1929) to the Far East examined many squirrels (Sciurus vulgaris mantshuricus Thom. 1909), and among other helminths found a new species belonging to the genus Longistriata Schulz, 1926 (subfam. Heligmosominae Travassos, 1914). The same species had also been found by one of us (M. P. L.) in Ussuri squirrels at the Moscow Zoo.

Five larval trematodes have been obtained from a search of many terrestrial molluscs. All are distome cercariae developing in sporocysts. One species appears to be Cercariaeum helicis Braun the sporocyst and cercaria stages of which are described here in detail. The other four species are new. Cercaria politae lucidae n.sp. and C. lauriae cylindraceae n.sp. the two Xiphidiocercariae described are rare in this locality, each species being found only on two occasions. The larvae obtained are also less abundant and less representative of the larval Trematode groups than those met with during my search of the local fresh-water molluscs for similar parasites (Harper, 1929, 1931).

During the investigation two new records have been added to the molluscan fauna of Forfarshire (Vice county, No. 90), viz. Polita lucida Drap., and Succinea elegans Risso. No helminth parasites were found in the last-named mollusc.

In conclusion, the following comments may prove suggestive:

Out of fifty-five vials of the Chinese cestodes from Charadriiform birds, fifteen have not been determined definitely, owing to the poorly preserved condition and to insufficient material for detailed study, such as Pe 510, Pe 517, Pe 526, Pe 529, Pe 552 b, Pe 588, Pe 593, Pe 1466, Pe 735 c, Pe 1431 d, Pe 760, Pe 144 b, Pe 151, Pe 848 and Pe 841 d.

In this paper, seven species are described as new, namely, Amoebotaenia fuhrmanni, A. pekinensis, Monopylidium guiarti, Choanotaenia joyeuxi, Haplo-paraxis sinenis, Fuhrmanniella clerci, and Gyrocoelia fausti.

The present study indicates, to a certain extent, that the Chinese fauna of the avian cestodes is more or less related to that of the Ural, Australia, Egypt and Europe.

Pe 848 is an interesting tapeworm recorded from the liver of Totanus calidris. Owing to the poor preservation, the strobilae can not be examined, but its incomplete rostellar hooks, larger 0·0234 mm., and smaller 0·0216 mm. shown in Fig. 54, are characteristic.

The British species of Aëdes, A.(Finlaya) geniculatus, lays its eggs on the damp surfaces of tree-holes containing water; or, if the expanse of water in the hole be large, often directly upon the water surface.

The two specimens of trematodes herein described were obtained from the intestine of an Indian Ruff, Philomachus pugnax. Of six birds examined, three harboured a few of both species. The genera to which these worms belong have not been hitherto recorded from India.

The following notes deal with nine species of parasitic nematodes from the Yangtze Valley and an additional one from North China. Of these ten species, one belongs to the super-family Rhabdiasoidea, three to Oxyuroidea, and six to Spiruroidea; three species have been previously described; therefore in these cases the writer gives only their measurements and a description of the particulars in which he found them to differ from the original description. Seven species Rhabdias annulosa n.sp., Pingus sinensis n.g. et n.sp. (Pingidae n.f.), Omeia hoepplii n.g. et n.sp., Thelazia chungkingensis n.sp., Oxyspirura kaitingensis n.sp., Oxyspirura peipingensis n.sp., Oxyspirura tsingchengensis n.sp., are new to science.

The value of precipitin and intradermal tests as a means of diagnosing trichinosis in man and swine is discussed. The precipitin test appears to be reliable in detecting established trichinosis in swine, and with the conditions under which the observations were made, is highly specific. Established trichinosis in man has been invariably detected by the precipitin test, but its diagnostic value is greatly diminished by the fact that it is also positive with serum from individuals who have recently received quinine treatment for malaria. Certain other drugs appear to affect this reaction in a similar manner. The intradermal test appears to be specific for trichinosis in man and swine when high dilutions of the test antigen are used. The reaction is positive in the early stages of the disease and is of the immediate type in both of these hosts. A survey of swine has shown that the precipitin and intradermal tests are more accurate than muscle examination.

1. Cephenomyia auribarbis Mg., a tachino-oestrid parasite of the red deer (Cervus elaphus L.), is distributed throughout the deer forests of Scotland. The adult is found on the wing during June and July.

2. The larva normally occurs attached to the walls of the nasal passages and pharynx, where it remains for 10 or 11 months. At maturity it drops to the ground and pupates beneath the surface. The adult emerges in 3–4 weeks.

3. In January, 1931, a larva of the early third instar was recovered from a stag shot at Blair Atholl, Perthshire. It was found in fat in the pelvic region and not in the nostril or pharynx as might have been expected.

4. It is suggested that the larva may have been swallowed by the host and bored its way through the wall of the gut into the peritoneal cavity, whence it had wandered to the pelvic region; or else that a first-stage larva had been accidentally deposited by a female on the hide and had bored through the body wall to the peritoneal cavity.

5. The adult female and the early third-stage larva are described and illustrated.

6. A comparison is made between the cephalo-pharyngeal apparatus of Cephenomyia auribarbis, Cephalomyia ovis, and Gastrophilus intestinalis. It is noted that the basilar sclerite of the first two species is provided with an accessory lateral appendage on each side. A greater surface is thus furnished for the attachment of the large depressor muscles of the buccal hooks. The larva thus securely holds its ground in the nasal cavities and pharynx, where the risks of summary ejection are always present. In G. intestinalis the accessory appendage is absent. The chances of the larva of this species losing its hold on the gastric mucous membrane of the host are very slight.

Description. Body more or less elongated, narrowing anteriorly and posteriorly. Length 1·34–1·441, maximum width 0·476, maximum thickness 0·433, both measured in the region of adhesive apparatus. Entire surface of the body, except adhesive apparatus and the region posterior to second testis, covered with fine spines. Ventral folds originate approximately at centre of body and meet a little behind the level of posterior third to form a shallow cavity occupied by the adhesive apparatus. Adhesive apparatus smooth, oval, 0·4–0–44 long, 0·26–0–3 wide, with narrow central depression, anteriorly reaching acetabulum and posteriorly anterior margin of posterior testis. In it are imbedded vitelline follicles, anterior testis, ovary and anterior portions of cirrus sac and uterus.

Seven species of cercariae and four of metacercariae collected at Roscoff, Finistère, during August, 1931, are described. They have been referred to appropriate systematic groups and wherever possible, probabilities concerning life histories are suggested. Four of the cercariae and two of the metacercariae are recorded as new to science.

1. A brief account is given of a schistosoma cercaria obtained from Bulinus truncatus possessing four pairs of flame cells in the body.

A monkey, Cercopithecus sebaeus, was experimentally infected with this cercaria, adult male and female S. haematobium being formed in the mesenteric veins, and terminal spined ova in the sub-mucosa of the colon.

The view is expressed that this cercaria was probably an aberrant form of the cercaria of S. haematobium.

Previous work on the effect of temperature and humidity upon the survival of unfed fleas is criticised in respect of experimental technique. In the present investigation measures have been taken to eliminate as many variables as possible and the methods employed to this end are described.

In the experiments, 2027 Xenopsylla cheopis, 999 X. astia and 646 Ceratophyllus fasciatus were employed, all unfed and less than 24 hours old at the commencement of the different experiments. Records were kept individually so that a statistical measure of consistency could be made.

The following conclusions have been reached:

(1) Duration of life of unfed fleas is not influenced by sex.

(2) High temperatures and low humidities tend to shorten life; conversely, low temperatures and high humidities, with a possible optimum of about 90 per cent., tend to produce longer lives.

(3) Humidity is at its maximum efficiency in this respect at about 18° C.

(4) At 37° C. humidity ceases to have any effect upon the duration of life of unfed fleas, and the evidence suggests that there is also a low temperature at which humidity has no influence upon survival.

(5) There is no direct proportion between survival of unfed fleas and saturation deficiency of the atmosphere at any temperature.

Comparing the species, it was found that:

(1) Ceratophyllus fasciatus was the longest lived, at similar atmospheric conditions.

(2) Xenopsylla astia lived longer than X. cheopis at all humidities at 23° C.

The material upon which the present paper is based is a part of Faust's valuable collection of avian cestodes from China. It was sent by Dr E. C. Faust, formerly Professor of Parasitology in the Peking Union Medical College, to the Zoological Laboratory, University of Neuchâtel. The collection, consisting of cestodes from charadriiform birds, was contained in 55 tubes.