On December 7th, 1968, Academician K. I. Skrjabin celebrated his ninetieth birthday and completed 63 years of his scientific career. From humble beginnings as a student of Veterinary Medicine and Natural History at Juriev University where he qualified in the year 1905, he has traversed the long path which led him to become a very distinguished scientist with an international reputation and one of the outstanding helminthologists of all time. His interest in helminthology began during his veterinary work in Central Asia where he made extensive collections of helminths from all groups of vertebrate animals. These he studied from 1912 to 1914 under the guidance of European specialists in helminthology, viz, with Professors Braun and Lühe of Germany, with Professor Fuhrmann of Switzerland and with Professors Railliet and Henry of France. His studies and publications at this time inaugurated Skrjabin as an erudite and accomplished helminthologist and his master's thesis, submitted in 1916, entitled: “Contributions to the characteristics of the helminth fauna of domestic animals in Turkestan” was a brilliant piece of work. In this he emphasised the necessity of establishing special chairs of parasitology and infectious diseases at Veterinary Institutes and Medical Faculties of Universities. A year later the first chair of parasitology was established, at the Novocherkassk Veterinary Institute, and Skrjabin was appointed to it, thus becoming the first professor of parasitology in the country.

1. The effect of relative humidity on the survival and development of Neoascaris vitulorum eggs to the infective stage is described.

2. Tables showing the percentages of eggs at different stages of development and dead eggs at weekly interval for two different sizes of faecal masses are constructed and the results discussed.

3. Detailed weather graphs showing daily rainfall, average daily relative humidity and evapotranspiration for Ibadan and Obudu during the rainy season of 1964 are constructed and the effect of the weather on survival of Neoascans vitulorum eggs in pasture at these places is discussed.

4. The minimum relative humidity for the survival and development of Neoascaris vitulorum eggs to the infective stage is found to be 80%. The period of survival of eggs in a dry atmosphere depends on the size of the faecal mass containing the eggs. The critical relative humidity for Neoascaris vitulorum eggs is compared with values for other ascarids of domestic animals.

This report is the third in a series by the authors on the digenetic trematodes of marine fishes from Ghana, and was supported in part by a State University of New York Faculty Research Fellowship (FRF 68–40–003) awarded to the senior author. Specimens have been deposited in the U.S. National Museum Helminthological Collection as indicated. All measurements are in microns.

The lungworm, Aelurostrongylus abstrusus, is a common parasite of the domestic cat in Great Britain and produces pulmonary lesions in that species which are occasionally severe. The disease may be reproduced experimentally either by the oral administration of third stage larvae which have been extracted from infected molluscs or by feeding the latter, themselves. For experimental purposes, the former procedure is preferred but the main disadvantage is that an infecting dose must be given on several occasions and over a period of days if sickness, with consequent loss of larvae, is to be avoided. Parenteral administration would, therefore, be advantageous. It is known that pulmonary infections have been produced in calves by the subcutaneous administration of larvae of Dictyocaulus viviparus (Wade and Swanson, 1958), in pigs by the intravenous and intratracheal injection of Metastrongylus spp. larvae (Kelley & Krous, 1961) and in sheep by the intravenous inoculation of Dictyocaulus filaria larvae (Michel and Sinclair, 1963). As neither intravenous nor intratracheal administration is particularly desirable in cats, it was resolved to attempt the reproduction of lungworm disease in that species by the subcutaneous injection of third stage larvae of Aelurostrongylus abstrusus.

1. One hundred and eight native domestic fowls and the same number of introduced birds were killed and examined for helminth parasites between July 1965 and April 1966.

2. Eighteen species of helminths were found in the native birds as opposed to ten in the introduced ones.

3. A detailed comparison of the incidence and intensity of is infection of the different species of parasites in each type of fowl given.

4. The frequency distribution of the number of species of helminths in both types of chickens follows a normal distribution, reflecting the multiple infection in the birds. The frequency distribution of the number of individuals of any one species approximately fits a negative binomial distribution.

5. In general, the native birds were found to be more heavily infected than the introduced ones. This is probably related to differences in host resistance, diet, sanitation and the type of poultry husbandry practised.

Through the generous co-operation of the British Antarctic Survey twelve Sheathbills were collected in April, 1967 at Signy Island, preserved in deep freeze, and made available to us for parasitological examination. Five of the Sheathbills were found to be infected with a new species of notocotylid trematode, namely Paramonostomum signiensis n.sp., which is described below and considered in relation to other species of Paramonostomum Lühe, 1909.

We have previously reported on the cestode and trematode parasites of the Sheathbill at Signy Island (Jones & Williams 1967, 1968, 1969) and conclude with an account of the nematodes and Acanthocephala. Our previous reports were based on specimens obtained from 13 Sheathbills collected at Signy Island in July and October, 1965 by Mr. Charles Howie, British Antarctic Survey. In addition to these we have examined a further 12 Sheathbills taken at Signy Island in March, 1967. We are greatly indebted to Mr. E. A. Smith, Senior Biologist, British Antarctic Survey, for arranging the collection and transport of the latter material.

1. In primary infections of chicks with 300 or 600 H. gallinae infective eggs, no clinical signs were apparent. Nodules were absent in all the experimental chicks as well as controls. Microscopically, few juveniles were observed in the caecal mucosa and the usual changes were mild congestion, few haemorrhages, and desquamation of superficial lining epithelial cells. Sections through a few thickened areas revealed a breached muscularis mucosa through which proliferated mucosal tissue had just invaginated into submucosa. The liver showed no changes.

2. With primary infection of chicks with 300 or 600 infective H. gallinae eggs, and their subsequent infection after 25 days with 1,000 infective eggs, there were no clinical signs after either primary or secondary infections. Nodules of varying sizes were present on the caecal wall of infected birds only, their size and number varying with age of infection. Histopathologically, the types of nodules observed were, one associated with juveniles and the other with their absence; and nodules were present both in the invaginated mucosa and in the submucosa. It was confirmed that these caecal nodules were due to irritation by H. gallinae juveniles and their metabbolites, and that these nodules were more a reaction of already sensitised caeca to subsequent infections, a fact hitherto unreported. The liver showed nothing abnormal, and there was not much difference between the haematological values of experimental and control chicks.

3. The actual process of formation of caecal nodules is demonstrated for the first time. The feasible explanation seems to be that on irritation of the already sensitised caeca by H. gallinae juveniles and their metabolites, hyperplasia of lymphoid tissue and epithelial cells results, which leads to a breach of the muscularis mucosa through which proliferated tissue of the mucosa invaginates. Later the muscularis mucosa constricts off and closes the nodule, the mucosa over it regenerates and becomes continuous. The present observations also indicate that the sterile nodular lesions usually found in natural infections may be the result of frequent infections, thus sensitising the chicks to subsequent infections.

1. Brachylaimus oesophagei Shaldybin, 1953 from the common shrew, Sorex araneus castaneus Jenyns is described and compared with that of Shaldybin (1953) and a closely related species B. fulvus Dujardin, 1843.

2. Despite unsuccessful attempts in hatching the egg of B. oesophagei, some morphological features of the miracidium are described and compared with previous studies on brachylaimid miracidia. Neither flame cells nor epidermal plates have been observed in miracidia of this family and present observations confirm this.

3. A description is given of the cercaria and metacercaria of B. oesophagei from the kidney of the hollowed snail Zonitoides excavatus (Bean) at Aberystwyth, but no sporocysts or cercariae were found in the digestive gland.

4. Previous work on brachylaimid life histories is discussed, together with a resumé of the life history of B. oesophagei.

1. The effects of a sublethal concentration (0·0165 p.p.m.) of N-tritylmorpholine on the development of S. mansoni in B. glabrata are described.

2. A total of 160 snails were infected with S. mansoni and then divided into 4 groups. Each group was treated separately with N-tritylmorpholine for a period of 24 hours.

3. The first group was treated 10 days after infection (early prepatent stage); the second group 20 days after infection (late prepatent stage); the third group 42 days after infection (patent stage); and the fourth group was left untreated and kept as an infected but untreated control group.

4. Three groups of uninfected snails were treated simultaneously with the infected groups, and a fourth uninfected group was left untreated and maintained as an uninfected and untreated control group.

5. In the early and late prepatent groups treated with N-tritylmorpholine a relatively short incubation period was observed compared with those in the patent and untreated infected groups.

6. No significant difference was observed between the cercarial infection rates of the 4 infected groups of snails (x2 = 0·744; p > 0·5).

7. In all infected groups peak cercarial production was observed about 15–20 days after the emergence of cercariae was first noted, after which numbers declined. No significant difference was observed between the total cercarial production of the early prepatent, late prepatent or patent groups and that of the untreated infected control group (p > 0·4).

8. The mortality rate of snails in the patent group was significantly higher than in the corresponding uninfected control group (x2 = 6·04; p <0·02).

9. Treated infected snails in all three groups ultimately had a lower survival rate than did treated uninfected snails.

10. The survival rate of untreated infected snails while initially as good as that of the untreated and uninfected group, was ultimately much poorer.

Over a period of seven years several series of observations were made on infestations of Ostertagia ostertagi and Cooperia oncophora on the herbage of pastures grazed by calves. A regular seasonal pattern was revealed. The concentration of larvae on the herbage falls to a low level in spring. Susceptible calves turned out at this time may begin to contaminate the pasture in mid-May but it is not until July that the infestation on the herbage increases significantly. Generally the increase is to a high level which is maintained with little change until the following spring.

Evidence is presented which indicates that contamination of the pasture in the first half of the grazing season is far more effective in the production of an infestation on the herbage than is contamination in the second half of the season.

In a discussion of the epidemiology of parasitic gastro-enteritis the formerly accepted view, that clinical helminthiasis results from a continuous build-up of infection in the calves and on the pasture is rejected. It appears that the parasites complete little more than one generation each year.

The results of these observations suggest a simple and widely applicable means of controlling parasitic gastro-enteritis in calves.

Le Roux (1930) erected the genus Ashworthius for nematodes, from Tragelaphus scriptus sylvaticus—the bushbuck, which closely resembled Haemonchus but which had a symmetrically placed dorsal lobe of the bursa and apparently lacked a gubernaculum. The four species of Ashworthius, so far discovered, are described as lacking a gubernaculum, but numerous specimens from Syncerus caffer caffer received by the author, and identified as A. lerouxi Diaouré, have a distinct gubernaculum. Paratype specimens of A. lerouxi and specimens of most of the other species were examined to determine if the gubernaculum is in fact absent. As a result of this study the genus is reviewed to correct errors in some of the published descriptions and to provide new information where possible.

Redescriptions of the cercaria, metacercaria and adults of N. triserialis and N. imbricatus are given. Cercariae developed in Lymnaea peregra and Bithynia tentaculata respectively and infected snails were collected from the Wentloog level, near Cardiff, South Wales. The characters adopted by Dubois for distinguishing species of this genus are more reliable than any alternative and the number of ventral glands is considered to be a reliable diagnostic feature in spite of suggestions to the contrary. The possibility of using chemical differences between the metacercarial cysts and other stages as a means of speciation is discussed.

This redescription is based on specimens taken from the leg of a moorhen, Gallinula chloropus (L.), that was found alive, but paralysed, in Adwick-le-Street, Doncaster, Yorkshire. The heel joints of both legs were distended and found to be infected with nematodes. The paralysis may have been caused by debility due to blood loss as a result of injury, rather than a direct effect of the parasite because a post-mortem examination also revealed “severe bruising of the right ribs and the liver had ruptured to produce an internal haemorrhage.”

The development of the parasitic stages of O. ostertagi is described and illustrated by a series of figures.

Experimental infections with strongyles were carried out using ponies reared worm-free. Infection with Strongylus vulgaris was produced by artificially administering larvae to housed ponies. Infection with small strongyles was produced both by this method and also by exposing hitherto worm free ponies to heavily infested pasture. The shortest prepatent periods found were: S. vulgaris, 149–156 days; Triodontophorus spp. and Poteriostomum spp., 63–70 days and trichonemid species 35–42 days.

Two males and one female Aphelenchoides were taken from the rootlets of radish, Raphanus sativus, in December, 1967, in the suburbs of Lucknow (India). They are described as new and are named Aphelenchoides franklini n.sp.

Experimental studies in mice have shown that with single sex female infections of S. mattheei there is a slow maturation of the worms with evidence of incomplete parthenogenesis; at 9 weeks no eggs were produced but at 17 weeks there was an average of 500 eggs per mouse. These were all non viable. Under similar conditions S. mansoni females failed to produce eggs.

When the females of S. mattheei were paired with males of S. mansoni, the females reached full maturity and produced large numbers of eggs typical of their own species-many of the eggs were non viable but some contained active miracidia.It is considered that this is an example of parthenogenesis and not hybridisation. Cross specific pairings of schistosomes must occur frequently in man particularly with S. haematobium, S. mansoni and S. mattheei and this phenomenon could be of considerable clinical, epidemiological and biological significance. Parthenogenesis in mixed infections probably accounts for the large number of non-viable S. haematobium eggs seen in rectal biopsies, and it may also be important in reducing the transmission potential of schistosomes to man since cross pairing must result in the “sterilisation” of a considerable proportion of the female worms in mixed infections. This phenomenon may also explain the observed reproductive isolation of schistosome species which simultaneously infect the same host.

The present paper deals with investigations on the occurrence in Netherlands' fresh water fishes and host specificity of tapeworms belonging to the genus Proteocephalus. The species involved are:

P. tetrastomus (Rudoiphi, 1810) in smelt, Osmerus eperlanus.

P. longicollis (Zeder, 1800) in smelt, Osmerus eperlanus.

P. cernuae (Gmelin, 1790) in pope, Acerina cernua.

P. ocellatus (Rudolphi, 1802) in perch, Perca fluviatilis.

P. macrocephalus (Creplin, 1825) in eel, Anguilla anguilla.

Seasonal cycles were found in P. telrastomus and P. ocellalus; in the latter species this was certainly induced by low winter temperatures.

Experimental infections showed that a high degree of host specificity exists in all species considered. Infections of an alien host were never successful. Two kinds of infections were carried out: (a) feeding plerocercoids (in the intermediate host), coming from a known source, to a number of fishes, belonging to several species including the original host species, and (b) transplanting worms, collected from the intestine of a fish, to the intestines of a number of other fishes, belonging to several species including the original host species.

Notwithstanding the high degree of host specificity, worms may survive for one or two days, but usually in a bad condition, in the intestine of an alien host. Occasionally they survived up to 14 days: e.g. P. tetratomus in Anguilla anguilla. Consequently sometimes dissections of predator fishes or carrion eating fishes may produce dubious host records because actually Proteocephalus from their prey are recorded. We are convinced that P. tetrastomus found in Salmo trutta, Platichihys flesus and Perca fluviatilis originate from Osmerus eperlanus having been eaten by these species.

Additionally cannibalism may be responsible for the fact that large specimens of some fish species, e.g. smelt, are heavily infected with Proteocephalus while they hardly eat any Cyclops, the intermediate host. This is clearly demonstrated by the transplantation experiments, transplanting worms to the proper host.

From the data recorded it is apparent that representatives of the genus Proteocephalus are not harmful to commercially important fishes in the Netherlands. In these fishes natural infection with the proper species of Proteocephalus is low and successful infection with other species, showing a high incidence in less valuable fishes, is prevented by the high degree of host specificity. Additionally worms of the species studied did not injure the tissues of the intestinal wall by the action of their suckers and piercing of the intestinal wall never occurred. Even smelts infected with large numbers of worms-more than 50 in a single 20 cm. specimen-did not show any abnormalities in genital development or in the amount of fat in the body cavity.

1. Four new species of the genus Diplectanum Diesing, 1858 are described. These are D. cupatum sp.nov. from the gills of both Epinephelus merra Bloch and E. fasciatus (Forskål), D. plectropomi sp.nov. from the gills of Plectropomus maculatus (Bloch), D. summanae sp. nov. from the gills of E. summana (Forskål), and D. vagampullum sp.nov. from the gills of E. merra Bloch.

2. Latericaecum gen.nov. and Monoplectanum gen.nov. are proposed to contain L. pearsoni sp.nov. and M. australis sp.nov. collected from the gills of Sphyraena obtusata Cuvier & Vallenciennes and Sillago ciliata respectively. Calydiscoides gen.nov. is proposed to contain C. australis sp.nov. from the gills of Lethrinus chrystostomu Richardson together with C. difficilis (Yamaguti, 1953) comb.nov., C. duplicostatus (Yamaguti, 1953) comb.nov. and C.flexuosus (Yamaguti, 1953) comb.nov.

3. Lepidotrema angusta (Johnston & Tiegs, 1922) Price, 1937 and L. bidyana Murray, 1931 are redescribed from fresh materials from the type hosts and the generic diagnosis is emended from a study of these specimens, new specimens of L. tenue Johnston & Tiegs, 1922, and named material of L. therapon Johnston & Tiegs, 1922.