Recent data indicate that platelets may play an important role in the host defence against Toxoplasma gondii infections. T. gondii-stimulated human platelets release thromboxane A2 (TXA2) and 12-hydroxyeicosatetraenoic acid (12-HETE) from arachidonic acid and 13-hydroxyoctadecadienoic acid (13-HODE) from linoleic acid (Yong et al. 1991; Henderson et al. 1992). We have previously demonstrated that the eicosanoid TXA2 has potent cytotoxic activity against T. gondii trophozoites (Yong et al. 1991). In this study, we examined whether 12-HETE, 13-HODE, and linoleic acid also have toxoplasmacidal activity. 13-HODE at concentrations ≥ 10−8 M rapidly induced cytotoxic changes in T. gondii. Ultrastructural changes induced by 13-HODE in T. gondii included an initial leakage of cytoplasmic contents into a space between the inner and outer parasite bilayer membrane units which was followed by intracellular vacuolation and loss of cytoplasmic contents. In contrast, linoleic acid and 12-HETE lacked toxoplasmacidal activity at 10−10–10−6 M concentrations. These data indicate that 13-HODE, a product of linoleic acid metabolism, has potent cytotoxic activity against T. gondii; this toxoplasmacidal activity may be important in the inflammatory response to this pathogen.

Owing to the kindness of Dr H. A. Baylis I have recently had the opportunity of examining portions of two species of Avitellmine tapeworms, both of which are new to Helminthology and both of which belong to a genus which is distinct from the two genera which have hitherto represented the Avitellininae. The material which I have examined is the property of and is deposited in the British Museum (Natural History) at South Kensington, London.

Exotic species can experience fast expansion in new environments, especially if they left their pathogens behind (Enemy Release hypothesis) or brought novel pathogens to the native competitors (Novel Weapon hypothesis). Common waxbills (Estrilda astrild) are native to sub-Saharan Africa and invaded west Iberia since the 1960s. Past haemosporidian parasite surveys at four locations in Portugal showed that waxbills can be infected with parasites, though with very low prevalence. However, it is not known if this pattern generalizes across their distribution range, or if there are geographic differences in parasite prevalence. It is also not discussed if this is a case of Enemy Release, as opposed to waxbills being also little parasitized in their native range. We screened 617 waxbills in 23 sites in Portugal and detected nine parasite lineages, most of them only known to the Palearctic. Only ten individuals were parasitized, and there was no significant geographical pattern on the prevalence. Overall, this population shows very low prevalence of haemosporidians (1.6% prevalence), which contrasts with significantly higher prevalence in native grounds, as compiled from the literature. These data support Enemy Release as the most likely hypothesis, which may have been important for their success as an exotic species.

Pseudodiplorchis americanus infects the urinary bladder of a desert toad and feeds exclusively on blood, producing the iron-rich waste product haematin. The host, Scaphiopus couchii, retains dilute urine within the urinary bladder as a water store throughout hibernation and parasite waste will therefore not be eliminated. This study utilized atomic absorption spectrophotometry to quantify the iron within the urinary bladders of infected and uninfected toads after different periods of hibernation. During the first 4 months hibernation, no detectable iron, above that of the controls, was found in the urine and bladder tissue of infected animals, but after 5–6 months hibernation there was a small but not significant increase. The iron contained within most individual parasites was greater than that detected in the urine and bladder tissue of the host, and the total iron in each parasite infrapopulation was 3–83 times greater than the urinary bladder iron. This suggests that the parasites do not regurgitate their gut contents during host hibernation. The amount of iron in individual parasites increased with time after migration to the bladder and this was used to estimate the amount of blood ingested by P. americanus. At a controlled temperature of 25 °C, the estimated rate of ingestion increased from 0·33 μl blood/parasite/week by worms 2 weeks post-migration to a maximum of around 1·6 μl by worms 5 months post-migration. The rate of blood ingestion by older worms was also calculated as a function of the hibernation period (since this did not correspond to worm age) assuming complete gut evacuation at the start of hibernation. This provided maximum estimates of ingestion rate of 1·9–5·3 μl blood/parasite/week.

A checklist is given of the 320 species and four subspecies of trombiculid mites of the Oriental and Australasian regions described up to the end of 1955, together with a number from papers being published in 1956 and 1957 and consulted by the writer in manuscript or proofs.

Eight new genera, six subgenera, and 175 species from the Oriental and Australasian regions have been described since the compilation of the checklist of world trombiculids by Wharton & Fuller (1952).

The present list gives only the documentation and records necessary to bring the appropriate part of Wharton & Fuller's publication up to date. Cross-references are given to the monograph by Womersley (1952) and its appendix by Womersley & Audy (1957), as well as to the checklists of Gunther (1952) and Radford (1954).

The taxonomic arrangement has been revised in accordance with recent publications. Four new combinations of species of Neotrombicula are recorded.

A supplementary Faunal List is presented, confined to records which now require to be added to the Faunal List of Wharton & Fuller.

This report documents the presence of an active thymidine kinase (TK) system within Mesocestoides vogae tetrathyridia as quantified by tritiated thymidine ([3H]-TdR) incorporation using liquid scintillation counting. A 100-fold increase in [3H]-TdR incorporation was observed at 37 °C when compared with its incorporation at 0 °C. Thymidine's competitive analogue, BrdU, competed for sites within newly replicated DNA. Immunohistochemical trials performed here using antibodies against BrdU identified cells that have entered and passed through S-phase. Positively stained nuclei were most numerous at the anterior tip of tetrathyridia especially within the ganglia, lesser numbers of these cells occurred along the growing commissure and amongst surface tegumental cytons suggesting that stem cells do not exist in one region but are found throughout the entire body. As M. vogae has no internal organ systems the major sites for cell proliferation are those exhibiting maximal cell recruitment and undergoing tissue repair. These results show that it is possible to monitor changes in the cell recruitment pattern within this cestode. Thus use of BrdU and immunohistochemistry demonstrates how spatial arrangement and cellular reorganization can be successfully traced within M. vogae.

The time taken for larvae of Nippostrongylus brasiliensis and a homogonic strain of Strongyloides ratti to complete their migration from the skin surface to the small intestine of the rat was estimated by a new method in which a mirror image of arrival times was created by counting mature parasites at day 8 (N. brasiliensis) or day 5 (S. ratti) in the intestines of rats that had received a single pulse of morantel tartrate by stomach tube at different times starting 10 h after skin application of exact doses of infective larvae. It was confirmed that the effect of the drug was confined to parasites in the gut, so that the kinetics of migration were unperturbed.

P. anoura was found in 55 % of pythons (M. spilotes variegatus) in Brisbane. Eggs contained first stage larvae after 8 days development; the first moult was completed by 10 days; the eggs were infective after 14 days. After ingestion by tadpoles, the larvae hatched from the eggs and migrated into the tissues but did not show any growth. In mice and rats the larvae migrated mainly to the liver, lungs and intestinal wall, where growth occurred to a length of 5–6 mm by 6 months after infection. The second moult was not observed, but the larvae were infective to pythons after 39–42 days development. From their structure it was assumed that after this time the larvae in mouse tissues were third-stage larvae.

Various species of Australian python, Morelia spilotes, Liasis amethistinus, L. fuscus and L. childreni, were experimentally infected with larvae of Polydelphis anoura by feeding nodules from the wall of the small intestine of experimentally infected mice and rats. The third moult occurred in the stomach within 14 days, moulting larvae at this stage measured between 3.5 and 7.0 mm long. Fourth-stage larvae occurred in all python species, the smallest being 4 mm. Growth and development of the fourth stage occurred at first in the oesophagus and stomach. Up to 2 months after infection, larvae had not grown more than 12 mm, yet they were clearly differentiated into males and females. In mouse-infected M. spilotes growth to 20 mm was reached by 154 days, but it was not until 183 days that adults were observed.

Comparison with adult specimens from P. reticulatus from Malaya confirmed the previous observation that Australian male specimens have relatively shorter spicules than male specimens from other geographical regions. Growth, development and location of larvae in mice, experimentally infected with eggs from Australian and Malayan specimens, appeared to be the same.

The fertility rate of eggs of the tick, Ornithodorus moubata, was investigated with the following results:

(1) Although three batches of eggs can be laid after a single mating, fertility is considerably improved if a fresh mating take place before each oviposition.

(2) Fertility of the eggs decreases with the interval between mating and oviposition (the latter takes place usually only after a blood meal).

(3) If the organ of Géné is faulty (permanently everted) none of the eggs will develop.

(4) Eggs have a wide tolerance of temperature, and show no alteration in fertility rate from 22 to 32° C. At 34° C. no larvae are produced at all.

(5) Females lay over twice as many eggs in sand as they do on a flat surface such as filter paper.

An account is given of ultrafiltration studies with Nicotiana virus 11 (tobacco necrosis virus). It is shown that though the filtration end-point is about 40 mμ, there is invariably a sharp drop in the local lesion counts between the membrane pore sizes 250 and 125 mμ. This phenomenon shows itself as a “bench” or shelf with an upward trend in the filtration curve (see Text-fig. 1, curve A). A number of possible explanations are given. The fact that increasing dilution raises the height of the bench leads to the deduction that large particles are breaking up into smaller ones, the larger particles being aggregates of the smaller. Experiments on resuspension of virus inside the filter and fractional filtration support the same conclusion.

From the filtration end-point the particle size of the virus is computed to be between 13 and 20 mμ.

By means of serial sections of experimentally infected Eisenia foetida with Metastrongylus spp. The distribution of larvae within the host has been determined. The exact position in the host intestine at which larvae penetrate has been shown to be the crop. The preferred site for localization and development of the parasite has further been shown to be the lamellar sinuses of the calciferous glands, although larvae were recovered from the dorsal blood vessel, hearts and perienteric blood sinuses. The way in which larvae pass from the gut to their definitive positions in the host has been discussed and it is supposted that this is determined by the configuration of the blood system rather than by a predilection for an environment low in free carbon dioxide. The pathology of infection and the distribution of alkaline and acid phosphatases, lipases, non-specific esterases RNA, DNA and haemaglobin have been described. The distribution of phosphatases in the gut is suggested to be concerned in the uptake of nutrients. The presence of an active zone of enzyme activity in the subcuticular regions of the parasite has been shown and the significance of this discussed. The parasite has been shown to feed directly on host blood.

Locomotion of adult Nippostrongylus brasiliensis has been studied in saline, in 0.6% agar, in sodium alginate of different viscosities and amongst sand grains in these media. In saline the nematode formed two-dimensional waves but there was little forward progression. Amongst sand grains in saline the nematode moved forwards by thrusting against sand grains, but thigmokinetic behaviour later resulted in quiescence. In 0.6% agar and in alginates of weak viscosity the nematode produced two-dimensional waves and sometimes a three-dimensional helical wave which resulted in forward movement. The formation of three-dimensional waves and the distance travelled increased with increasing viscosity up to 4% sodium alginate and also amongst sand gains in these media. In 8% sodium alginate the nematode became coiled like a spring but remained almost stationary. The three-dimensional wave is formed with torsion and obtains thrust from the viscous medium. In the intestine of the host thrust will be obtained from the mucus and villi of the intestinal mucosa. The ability of this nematode to move by two-and three-dimensional undulatory propulsion is probably related to its complex ridged cuticle. Attention is drawn to the role that increased viscosity of mucus may play in entrapping nematodes during their immune rejection.

Observations on 5 different isolates of Eimeria stiedai from pure infections in laboratory-reared rabbits have confirmed the presence of an oocyst residuum. This structure was seen in 89–100% of the oocysts in cultures prepared both from the liver and from the faeces at different times during the patent period. The residuum consisted of 1–7 or more granules situated centrally in the oocyst and partially concealed by 4 sporocysts. The differential diagnosis of E. stiedai and E. coecicola is discussed.

Some species of Nycteribiidae have been recorded from widely different faunistic regions. Thus, Eucampsipoda hyrtlii has been recorded from Africa, Ceylon, Burma and Sumatra. Other species have been recorded from Europe and China or from Europe and South Africa. Re-examination of the material has proved in most cases that the species were wrongly identified and no species has been found so far to exist both in Europe and in East Asia. There remained finally two species which have been recorded from the Ethiopian and the Oriental region, Tripselia blainvillii and Basilia bathybothyra. Material of these two species from as many localities as possible was therefore brought together, in order to determine whether this wide distribution does in fact occur or whether, in these cases as well, there existed different forms, species or subspecies, with a narrower range of distribution.

The following observations are the result of two years' examination of the stools of patients invalided to and stationed in Malta. The patients may be roughly divided for convenience into four groups:

(1) Troops sent straight from the Salonika Hospitals to Malta. This section comprised the bulk of the total number of troops examined, and included a few men from Egypt.

(2) Garrison Troops—some not patients—including both British and Maltese. With these are included a few British and Maltese Civilians,. connected in some way or another with the Army.

(3) Troops on their way out from England or France. These were mostly Indians and Chinese, who were put off transport at Malta owing to disability.

(4) Prisoners of War interned in Malta.

The development of the egg-shell of the trichuroid nematode, Trichuris muris, was observed by light and electron microscopy. Initial stages of shell formation occurred immediately following sperm entry into the oocyte in the spermatheca of the female worm. The external vitelline layer separated from the oolemma, reticulate oocyte granules were discharged into the resultant perivitelline space and stored glycogen contributed to the formation of the chitinous shell. A lipid layer developed between the inner surface of the chitinous layer and the oolemma. The fully formed egg-shell thus comprised an external vitelline layer, a middle chitinous layer and an inner lipid layer. The outer vitelline layer resembled a unit membrane with strands of particulate material attached to its outer surface. The middle chitinous layer was composed of chitin microfibrils encased in a protein coat; the sheets of microfibrils were arranged as parallel lamellae forming a helicoidal architecture. The inner lipid layer contained a variable number of loosely arranged strands of electron-opaque and less-opaque material.

Cercaria strigata was first named and described briefly by Lebour (1908) from Tellina tenuis and Donax vittatus at Alnmouth, Northumberland. It was recorded again by the same author (1911) in 3% of Tellina tenuis at Millport. What was almost certainly the same cercaria had been previously noted by Giard (1907) between the mantle and shell in the same hosts. Giard did not name or describe the cercaria but suggested that it was the young stage of Gymnophallus oedemiae (Jameson) (= G. somateriae (Levins)) from the scoter Oedemia nigra L.

Worm expulsion of, and IgE and interferon (IFN)-γ responses to, Nippostrongylus brasiliensis were studied in 2 rat strains, Brown Norway (BN) and Fischer (F)-344. BN rats expelled the majority of worms by day 14 post-infection (p.i.) with approximately 6% of worms surviving for at least 3 weeks. In F-344 rats, worm expulsion was delayed by 2 days relative to that in BN, while the numbers of residual worms were significantly fewer than in BN, suggesting that different immune mechanisms are involved in early and late phases of immunity. Total serum IgE, as well as in vitro IgE production by mesenteric lymph node (MLN) cells, was increased 2 weeks p.i., the levels being markedly higher in BN than in F-344 rats. Serum rat mast cell protease II was also increased more significantly in BN than in F-344 rats. In contrast, production of IgG2a and IFN-γ by MLN and spleen cells was found to be higher in F-344 than in BN rats. These results indicate that the early worm expulsion is correlated with the host IgE and mast cell responsiveness, whereas the persistence of infection in the late period may be controlled by different immune mechanisms.

The material described in this paper was obtained from a mongoose (Herpestes albopunctatus Hodgson 1853), dead twelve hours when dissected. In the mesentery were numerous larval cestodes and in the intestine approximately fifty adults of another species. The preservation was good. The preservation was good. I wish here to acknowledge my indebtedness to Mr G. D. Bhalerao, M.Sc., of this University, for the help given me in the preparation of the specimens.

In a recent paper Dr L. R. Cleveland (1938) has published some observations on a remarkable flagellate called “Teranympha”, which was discovered nearly 25 years ago by Dr M. Koidzumi in the white ants of Japan. I do not now propose to discuss this singular organism itself, however, but only its name and certain other matters of wider interest which its nomenclature suggests—matters which seem to me, indeed, to merit the immediate attention not only of all parasitologists but even of zoologists generally.