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.

From time to time the writers have noted some items pertaining to nematode taxonomy that appeared to require some clarification. In this connexion the following brief notes have been assembled and are presented with the hope that they may prove useful.

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.

Studies were carried out in mice and a monkey (paratenic hosts) and pathological lesions in mice have been described in liver, lung and brain with Toxocara larvae moving actively in the tissues causing damage (haemorrhages and necrosis) with encystment. In both mice and monkey there is essentially an eosinophilic response with lymphocytes and neutrophils also showing rise in the peripheral blood a few days after infection. In mice lymphocytes are the predominant tissue inflammatory cell.

Deaths due to infection with Streptocara crassicauda (Creplin, 1829) occurred in three ornamental flocks of water fowl in Hampshire. On two occasions larvae of the worm were found in Gammarus sp. in the running water to which the flocks had access. Lesions were almost entirely in the oesophagus and pharynx, and death was usually due to necrosis, and consequent impaction, of the oesophagus It appears that the worm is capable of establishing itself in southern England.

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.

Orientatractis leiperi n.sp. (Atractidae) is described, from the intestine of a South American tortoise. It is characterised by a cephalic armature of remarkable symmetry and complexity and by the presence of 3 tripartite structures in the anterior end of the oesophagus.

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.

Inhibition of development in the larvae of Ostertagia spp. infecting tracer lambs under field conditions shows a seasonal pattern (Connan, 1968) somewhat similar to that seen in O. ostertagi infections in calves (Anderson, Armour, Jennings, Ritchie and Urquhart, 1965). This finding also agrees with the seasonal appearance of dormant larvae in ewes (Soulsby, 1966; Connan, 1968) and one year old sheep (Parnell, 1962; James and Johnstone, 1967).

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. Eggs of Contracaecum osculatum, extracted from grey seal faeces, have been hatched in the laboratory at different temperatures and the morphology and behaviour of the larvae described.

2. Artificial exsheathment of the second stage larva from the first stage cuticle has been demonstrated.

3. In attempting to establish the first intermediate host of the life cycle, two species of harpacticoid copepods have been successfully infected but no significant developments reported.

The development of the reproductive system of O. circumcincta is described and the developmental cycle divided into phases. It is suggested that these defined phases can be used to give an accurate profile of a worm population. The population of worms found in the experimentally infected lambs is defined in terms of these phases, linear measurements and, in the mature female worms, the presence or absence of the vulval flap.

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.

The course of infection of chickens experimentally infected with C. nilesi suggested an immune response against the microfilariae. Autopsy findings of 6 experimentally infected chickens are given. In a chicken which received 32 infective larvae, when the peripheral blood was microfilaria negative for a period of 10 days, autopsy revealed 2 live active female and 3 live active male adult worms. These, when implanted in a clean 3 week old experimental chicken, produced a peripheral microfilaraemia for a further 63 days. When no peripheral microfilariae were detected for a period of 17 days, the recipient chicken was autopsied and microfilariae were found in the lung impression smears, although none of the implanted adult worms were found.

The morphology, structure and nocturnal subperiodicity of the microfilariae are described.

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.

Experiments were carried out on the migration, distribution, longevity and pathogenicity of larvae of Aelurostrongylus abstrusus in Helix aspersa. Snails placed in contact with several hundred thousands of first stage larvae, were examined from one to 24 hours until two years after infection. Larvae were first noted in the snails 4 hours after first contact and it was concluded that the migratory phase lasted for approximately 48 hours. Larvae were restricted to the deeper layers of the sole and to adjacent organs while the greatest number recovered from any snail was 1437. Larvae were at first surrounded by an accumulation of macrophage-like cells; this reaction declined and disappeared until by 12–24 months after infection only a single layered connective tissue capsule separated the parasites from the host tissue; sometimes even that structure was lacking. Larvae isolated from snails up to two years after the initial infection, were able to produce parasitic pneumonia in experimental cats. To study possible pathogenic effects of larvae on snails, a group of the latter were kept in constant contact with first stage larvae. One snail died at 15, three at 17, three at 19 and five at 27 days after initial contact, but despite the different exposure periods there was little variation in the number of larvae recovered from each snail. In addition, only third stage larvae were isolated from the last five survivors, which suggested that there was an immunological response by the snails. The importance of these results is discussed.