Microfilariae of Chandlerella hawkingi, a filarial parasite of the Indian jungle crow Corvus macrorhynchos Wagler, have been studied using the special staining techniques of Laurence and Simpson (1969). At the tip of the cephalic space a fang-like hook, bifurcated at the base, was visible. Near the hook four equilateral triangle-shaped spines could be seen arranged in a transverse row. There is a well defined oral ring. The pharyngeal thread starts as a funnel-shaped structure to end in the Innenkorper situated in the posterior third of the body.

Observations have been made on the survival and migration of infective larvae of strongylid nematodes of the horse deposited on outdoor herbage plots. Few larvae ascended the herbage when conditions were very dry and migration was often enhanced by falls of rain. Larvae on the herbage died rapidly during summer but there was a much slower mortality rate during the winter months. An appreciable proportion of larvae placed on the plots in late summer and autumn survived until the spring but, at this time, there was a rapid disappearance of larvae which coincided with the rising temperatures.

Adult stages of Euclinostomum heterostomum (Rudolphi, 1809) were collected from the oral cavity and oesophagus of Bulbicus ibis in Liberia, West Africa. Structural relationships within the trematodes are clarified. A prepharynx from the oral sucker leads to a well developed pharynx to which the intestinal caeca communicate via a bulb-shaped oesophagus. The origin and extent of gonadal ducts are described including a Laurer's canal, whose aperture is dorsal. A discussion of the characters previously used to differentiate species of Euclinostomum corroborates the views expressed by Ukoli (1996) that the genus consists of two distinct species, E. heterostomum (Rudolphi, 1809) and E. multacaecum Tubangui and Maslungan, 1935. E. shrjabini Kurashvili, 1948 is proposed as a synonym of E. heterostomum. A compilation of the range in measurements of the adult and metacercarial stages of E. heterostomum is presented in the form of a table.

The phasmids of the first-stage larva of Dracunculus medinensis were paired, each consisting of a single cell with a lumen connected to the exterior by a closable duct. The cell consisted of an outer region filled with mitochondria and an inner region consisting of endoplasmic reticulum bordering the lumen, whose inner surfaces was supported by a fibrillar framework. There were a pair of cilia projecting into the lumen of each cell and two nerve bundles at the base in direct continuity with a branch of the lateral nerve. The lumen of the phasmidial cell contained acid mucopolysaccharides and esterases.

Growth rate and activity of 10 nematode trapping fungi, (Hyphomycetes)—Arthrobotrys oligospora, Dactylaria brochopaga, D. gamsospora, D. polycephala, D. thaumasia, D. vermicola, Monacrosporium (Dactylella) bembicodes, M. {D.) cionopaga, M. {D.) ellipsospora, Trichothecium cystosporium—against the infective larvae of Ostertagia ostertagi and Trichostrongylus axei were studied. Species forming adhesive networks grew faster than the others. Species producing adhesive knobs, adhesive branches and constricting rings were, in general, slow growers.

The worm recoveries of two strains of S. haematobium from male hamsters and their egg laying capacities are studied. The infection rates obtained, the size of worms, and the number of testes and the distribution of eggs in hamster tissues are compared with those described for other strains of S. haematobium. It is emphasized that infra-specific variations in the host may also, in part, account for many of the differences that are attributed to different geographical strains of the parasite.

Development of the infective metacercaria of Mesostephanus yedeae Dennis and Penner, 1971 included: (a) ceicarial penetration and encystment in striated muscles, brain, liver and eye of Poecilia reticulata Peters; (b) a quiescent phase of nine days when no observable morphological change occurred; (c) a period of morphogenesis when an adhesive organ and a posterior body segment were differentiated. The time required for development to the infective metacercaria was delayed by decreasing the temperature of the fish host environment. The quiescent phase exhibited the greatest effects resulting from lowered temperature. Radial muscles and glands of the adhesive organ originated from parenchymal beta cells. The posterior appendage issued as a dorso-posterior evagination of the metacercarial body. Effects of the metacercaria on host tissues resulted in formation of a fibrous capsule in striated muscles, a granulomatous-like response in liver tissue, and necrosis of nervous tissue of the retinal complex which terminated in blindness of the infected eye. Effects of the adhesive organ on duodenal villi of the definitive host included “tearing” of the lamina propria and “pinching off” of pieces of duodenal epithelium.

1. Observations were made on various methods of infecting S. ornatum with 0. gutturosa, the behaviour of the parasite in its vector, and the maintenance of the vector in the laboratory.

2. S. ornatum reared from pupae brought into the laboratory were successfully infected with 0. gutturosa after feeding on infected cattle. The use of in vitro methods of infection was unsuccessful as microfilariae were ingested but did not undergo larval development.

3. The migratory route of 0. gutturosa microfilariae ingested by S. ornatum was studied and it was found that a mean of only 25% penetrate out of the abdominal midgut. The dimensional changes of 0. gutturosa were noted from the time of ingestion by S. ornatum until the infective stage was reached.

4. 0. gutturosa took 13–15 days to reach the infective stage in S. ornatum when maintained at a constant temperature of 23°C.

5. The development and structure of the peritrophic membrane of S. ornatum are described.

6. Preliminary observations on the seasonal variations of some factors affecting the transmission of O. gutturosa by S. ornatum suggest that microfilariae were only available for ingestion during the period of vector activity, after which they migrated into the deeper regions of the skin of cattle.

The morphologies of the adult worms and microfilariae of Ochocerca found in the neck and gastro-splenic region of cattle in southeast England were compared. It is concluded that they are forms of the same species.

1. 903 horses were examined at 3 abattoirs in South East England. 10(22–7%) of the horses at the London Colney abattoir, 23(13–9%) of those at the Braintree abattoir, Essex, and 90(12–9%) of those at the Islington abattoir, London, were infected with O. cervicalis. All 105 horses examined in Southern Ireland were found to be negative.

2. The adult worms of O. cervicalis were found without exception, in the ligamentum nuchae of infected horses. The suspensory ligaments of the fetlock and flexor tendons were always negative.

3. The microfilariae of O. cervicalis concentrate along the abdominal mid-line of the host. In 5 complete horse hides, 95% of the microfilariae were found within 6 inches of the linea alba. The examination of 31 other horses infected with O. cervicalis confirmed this pattern of microfilarial distribution.

4. The microfilariae were concentrated along the ventral mid-line, of the host; presumably an adaption to accommodate the habits of the vector C. nubeculosus, which bites preferentially in this area.

5. Seasonal variations in the number of microfilariae in horse skin, as reported by Japanese workers, was not observed. Evidence was found, however, to suggest that the microfilariae migrate into the deeper levels of the dermis during the Winter. Histological examination of infected horse skin showed that the microfilariae have a very uneven distribution in the dermis. They congregate together in isolated “clumps” or “nests” and are frequently found in close proximity to the sweat glands or hair follicles.