The following brief communication presents another instalment of experiments on the effects of prolonged direct transmission upon trypanosome strains kept up in the laboratory.

It has been found by use of electrophoresis that the hepatopancreas of the snail Biomphalaria alexandrina (Ehrenberg) contains one phosphoglucoseisomerase. Snails which have secondary sporocysts of the trematode Schistosoma mansoni contain an additional phosphoglucoseisomerase which is also found in the adult trematode. It is supposed that the secondary sporocysts are secreting phosphoglucoseisomerase into the hepatopancreas of the snail in order to increase the transformation of glycogen to simpler carbohydrates, in which form the parasite is able to absorb the carbohydrates necessary for metabolism.

American trypanosomiasis is a neglected tropical disease whose spectrum has not been quite understood, including the impact of Trypanosoma cruzi infection on the haematological parameters of different vertebrate hosts. Thus, this study was designed to compare the pattern of haematological changes induced by T. cruzi infection in order to identify possible species-specific differences among taxons. We also aimed at evaluating the use of this parameter as a tool for diagnosis during the acute phase, when symptoms are usually masked. For this purpose, we performed a systematic search on PubMed and Scopus databases to retrieve original studies published until August 2016. Thirty-one studies were selected using Prisma strategy, which were then submitted to data extraction and methodological bias analysis. Half of the studies showed that the number of erythrogram decreased in infected animals, indicating anaemia. In 68.2% of the studies, the total amount of leukogram values increased, suggesting infection. The main methodological limitations were insufficient information for T. cruzi strains identification, inoculation routes and parasitological characterization. Most of the mammalian species analysed showed the same pattern of haematological changes following T. cruzi infection, indicating that haematological parameters might direct the diagnosis of Chagas disease in the initial phase.

The host of the Coccidian described in this paper is Hydroporus palustris L., a small Dytiscid beetle common in stagnant ditches. The infected material was collected from two ditches in the neighbourhood of Grantchester (Cambridge). From one ditch 25 per cent. of the beetles were parasitised, and from the other ditch 15 per cent. were parasitised. The infection with Legerella, which is confined to the malpighian tubules, is often very intense. Heavily infected beetles are readily recognised on dissection because the malpighian tubules are colourless and do not contain the brown excretory granules characteristic of the normal tubules. The parasite has been observed at all seasons of the year, and the life cycle does not appear to follow a seasonal course.

In 1911, I received from Dr Georgina Sweet of Melbourne University, two lots of Trematodes stated to have been collected respectively from the intestine of the tiger snake, Notechis scutatus, and the lungs of the copperhead snake, Denisonia superba. In 1916, Dr Burton Cleland, of the Bureau of Microbiology, Sydney, sent me two tubes containing similar parasites, obtained from the peritoneum of an unidentified snake killed on Flinders Island.

Multiple infections, those by more than one parasite in the same erythrocyte, may be adaptive for the malarial parasite as a means to ensure fertility. Alternatively they may simply be the consequence of a non-adaptive process forcing several parasites to compete for resources in one host cell. Avian hosts infected with Haemoproteus were medicated with primaquine or injected with saline solution and the density of infection and number, maturity and sex of mature multiple infections counted. Multiple infections depend on density of infection, and maturity is attained rarely and usually by gametocytes of the same sex. The role of multiple infections for fertility insurance is not supported by these results.

1. A technique is given for the detailed study of living cercariae in which reference is made to the value of human or horse blood serum as a mounting medium.

2. As a fixative agent for cercariae prior to staining the use of hot lacto phenol solution is recommended.

3. A description is given of three non-furcocercous cercariae obtained from Bullinus contortus in the Sudan.

Obligate symbionts may be genetically structured among host individuals and among phenotypically distinct host populations. Such processes may in turn determine within-host genetic diversity of symbionts, which is relevant for understanding symbiont population dynamics. We analysed the population genetic structure of two species of feather mites (Proctophyllodes sylviae and Trouessartia bifurcata) in migratory and resident blackcaps Sylvia atricapilla that winter sympatrically. Resident and migratory hosts may provide mites with habitats of different qualities, what might promote specialization of mite populations. We found high genetic diversity of within-host populations for both mite species, but no sign of genetic structure of mites between migratory and resident hosts. Our results suggest that, although dispersal mechanisms between hosts during the non-breeding season are unclear, mite populations are not limited by transmission bottlenecks that would reduce genetic diversity among individuals that share a host. Additionally, there is no evidence that host phenotypic divergence (associated with the evolution of migration and residency) has promoted the evolution of host-specialist mite populations. Unrestricted dispersal among host types may allow symbiotic organisms to avoid inbreeding and to persist in the face of habitat heterogeneity in phenotypically diverse host populations.

Aplopabaksis filum (Goeze, 1782), A. clerci Yamaguti, 1935, and A. brachyphallos (Krabbe, 1869) are closely related species that are distinguishable mainly on anatomical characters, their scolex structures being remarkably uniform both in size and form. This opportunity is taken of defining the main diagnostic characters of the three species from an investigation of material collected in the Aberystwyth area of Wales.

Specimens of Plectanocotyle gurnardi were obtained by the writer from the gills of Trigla cuculus L. and T. gurnardus L. during trawling operations at the Irish Atlantic Slope fishing grounds in August 1938 and July 1939. One specimen of Plectanocotyle gurnardi was collected from a Trigla gurnardus and seven specimens of the same parasite from eight specimens of T. cuculus, the greatest degree of infestation encountered being 3 parasites per host fish. Plectanocotyle gurnardi has been recorded previously, under one or other of the synonyms listed above, from Trigla gurnardus by van Beneden & Hesse (1863), T. Scott (1901, 1905), A. Scott (1904), Lebour (1908), and Little (1929); from T. lucerna L. by A. Scott & Little; and from Trigla ‘sp.’ by Monticelli (1899). It will be noted that the present records of the parasite are from its usual host T. gurnardus and from a new host T. cuculus.

(1) Spermophilus columbianus, S. franklinii, S. lateralis tescorum, S. richardsonii, S. tridecemlineatus and s. undulatus plesius (ground squirrels) were collected from Alberta and Yukon Territory (S. u. plesius only), Canada. Trypanosome infections were detected in all but S. l. tescorum.(2) All six species of squirrels were experimentally inoculated with trypanosomes from naturally infected S. columbianus, S. franklinii, S. richardsonii and S. tridecemlineatus. The strains from S. columbianus, S. richardsonii and S. tridecemlineatus produced infections in some or all of the other host species, whereas the strain from S. franklinii did not.(3) Natural transmission of trypanosomes has not been demonstrated, but it seems likely that fleas act as vectors.(4) Intensities and durations of experimental infections were variable and depended upon the trypanosome strain, host species and individual. Infections were non-pathogenic.(5) Previously infected ground squirrels could not be reinfected with the same or a different trypanosome strain and immunity appeared to be lifelong.(6) Size comparisons among and within trypanosome strains from naturally and experimentally infected ground squirrels revealed that the strains from S. franklinii and S. tridecemlineatus were similar to one another, but different from the other three trypanosome strains (those from S. columbianus, S. richardsonii and S. undulatus).(7) It is suggested that there is only one species of trypanosome, Trypanosoma otospermophili, in the genus Spermophilus in North America and that differences in size and types of infection are due to host-induced variations (i.e. they are plastoxenodemes). T. spermophili (present in Eurasian Spermophilus spp.) might be synonymous with T. otospermophili.

This paper contains a discussion of the generic and specific characters of Tricho-nympha and Pseudotrichonympha, with a detailed account of the morphology of P. sertaneja n.sp. from a new species of Rugitermes.

The basic generic and specific characters of each organelle of Pseudotrichonympha are considered in detail. The genus Pseudotrichonympha has been separated from Trichonympha by the absence of the rostral articulation (citartrosi) and parabasal body. But in at least two species of Pseudotrichonympha a parabasal body has been found, and as Grassi himself believed that citartrosi, however feebly developed, must exist in all Pseudotrichonympha, the taxonomic position of Pseudotrichonympha needs further investigation.

The morphology of P. sertaneja n.sp. has the basic generic characters. The specific characters are discontinuous myonemes, oblique instead of longitudinal leiotropic striae, flagella of the first series covering not only the neck but the upper portion of the body, flagella of the second series confined to the basal part of the anterior triangular area of the body, flagella of the third series very short and of uniform size and simple outline of the ectoplasm.

The flagellate is regarded as a new species, named P. sertaneja n.sp. The host is a new species of Rugitermes from São Paulo, Brazil.

Centrocestus formosanus is a digenetic trematode from Asia that parasitizes multiple hosts and is a concern in the Comal River, Texas, USA, because of its negative effects on the endangered fountain darter Etheostoma fonticola. To determine a practical sampling method to monitor C. formosanus in the Comal River, we evaluated three sampling methods using wild-caught fish, caged fish reared in the laboratory, and cercariometry. Cercariometry detected significant spatial and temporal patterns of cercarial density in river water that were similar with metacercarial intensity in caged fish, but inconsistent with metacercarial intensity in wild-caught fish. Our results also showed a positive correlation between cercarial density in river water and metacercarial intensity in caged fish. Conversely, the relationship was not significant between cercarial density and metacercarial intensity in wild-caught fish. Because cercariometry predicted similar trends with the caged fountain darter sampling method, cercariometry was useful in predicting C. formosanus gill infections, infection rate, and longevity in infected fountain darters. Although trends from cercariometry and caged fish sampling methods were similar, we recommend cercariometry because it was less expensive to use given the amount of sampling effort required and provides trends that can be used to make pro-active management decisions in C. formosanus-infested aquatic ecosystems.

The paper records the description of the morphology and taxonomy of a new genus and species of a Heterotrichous ciliate (family Clevelandellidae) found in the gut of the non-xylophagous termite Capritermes incola Wasm. (Termitidae) from Dharwar (India).

Bloodmeal volumes and haemolysis rates were determined in male Argas (Persicargas) arboreus and A. (P.) persicus fed on pigeons, domestic fowl, and adult and fledgling herons. Erythrocyte osmotic fragility curves were prepared for the host species.

A new species of larval trematode, C. projecta, infects Helisoma antrosa. The very small distome cercaria is ontogenetically young, showing no traces of reproductive anlagen even after excystment. It belongs to the cystophorous cercariae, and has a vesicular tail into which the body of the cercaria withdraws when mature. In this encysted state the cercaria is expelled from the snail and awaits ingestion by the next host. The redia is a large, elongate sac, without “feet,” possessing a small pharynx, short intestine and an excretory system consisting of a longitudinal channel and at least sixty flame cells on each side of the body. Excystment is caused by mechanical pressure which releases a force within the cyst, which projects the cercaria very rapidly through a long cuticular tube, the excretory projection, to a considerable distance away from the cyst. Various complex appendages of the tail vesicle along with parts of the excretory system play a large part in this process of excystment. As postulated, the purpose of this type of excystment is to throw the larva away from its cyst, to prevent it from being regurgitated from the body with the empty cyst.

Studies on the susceptibility of the guinea-pig to infection with Schistosoma spindale Montgomery are reported.

Of twenty-two guinea-pigs, examined 33–153 days after exposures to 8000–50,000 cercariae of S. spindale, seventeen furnished conclusive evidence of the development of the female schistosome and two furnished inconclusive evidence. The male S. spindale developed in all the animals.

The female schistosomes attained maturity in 48 days or more and laid viable ova which could be detected in the liver, intestinal wall and lungs, but not in faeces.

The pathological lesions caused by the parasite consisted of thrombosis in the liver and lungs due to adult worms and pseudotubercles in the liver and nodules in the intestinal wall due to the eggs.

The guinea-pig shows varying degrees of individual susceptibility to infection with S. spindale and is an unsuitable host for the parasite, more especially for the female schistosome.

When fresh-water snails are examined microscopically, specimens are occasionally encountered that are infested with the cercariae of more than one species. Sometimes these cercariae are easily differentiated. A snail may harbour numerous eye-spotted amphistomes and a few distomes without eye-spots, or furcocercous forms may be associated with cercariae possessing undivided tails. In some collections of semi-stagnant water, however, the same individual snail may be found infested with at least two distinct schistosomes. In 1916, I found Physopsis africana (in an overflow pool along the course of the Umsindusi river at Pietermaritzburg) heavily infested with two distinct schistosomes, and it was not uncommon, as Dr E. E. Warren also observed, for the two forms to develop in the same host. One of these cercariae I named Cercaria secobii, the other was probably the cercaria of Schistosoma haematobium. Soparkar (1921 a and b) has moreover noted a double infection of Planorbis exustus near Bombay.

Estimates were made of the intake of strongyloid infective larvae by sheep at pasture by the recovery of larvae from samples of herbage collected through oesophageal fistulae.

All herbage eaten was not recovered through the fistula but few larvae were lost in the process of mastication and swallowing. More larvae could be recovered from macerated than from undamaged herbage.

Samples were obtained from different sheep on different days and at different times during the day and the variance components associated with these factors were estimated from seven sets of observations. The contribution to variance differed widely for each factor with the major contribution coming from time changes in the differences between sheep.

The authors wish to thank Mr G. W. Major for valuable technical assistance throughout these studies.

The anatomy of Köllikeria filicollis (Rudolphi, 1819), Cobbold, 1860 (Trematoda: Digenea) is described in detail.

An account is given of the integument and musculature of the worm and the structure of the cyst in which it is found, followed by a discussion of the body wall in other digenetic trematodes. The alimentary canal, excretory system, nervous system and genitalia are also described.

The study shows that the sexes are not entirely separate in all members of the genus Köllikeria as hitherto believed.

The systematic position of K. filicollis is discussed and a specific diagnosis is given for the species.