A technique is described for the recovery of strongyloid infective larvae from bulk pasture samples. Pasture sediment washed from herbage is first concentrated, and then larvae are separated by subjecting small portions of sediment to the influence of a slow vertical current of water in a specially-designed column. A more rapid flow of water into the separation apparatus at frequent intervals agitates the sediment and releases trapped larvae into the upward flow. Several sediments can be processed simultaneously using columns arranged in parallel. Larvae separated from sediments are counted by a KI flotation technique.

The penetration of the juveniles through the intestinal tissue caused breakdown of the carbohydrate complexes present in the area and in general the infected intestinal tissue had low carbohydrate content as compared to the control as revealed by several staining procedures. Results of the tests for lipids and proteins were not conclusive. The cytoplasmic RNA of the infected intestine and skin became more pyroninophilic and could account for an increase of RNA content in the infected tissue.

There was an increase of the alkaline phosphatase activity and a decrease in the fibrin content in the infected intestine. Tests for pigments and amyloid and hyaluronidase extraction procedures were inconclusive.

1. Laboratory studies showed two types of cages to be suitable for exposing uninfected B. glabrata in field habitats as a means of locating S. mansoni miracidial infestations.

2. Tests conducted in tanks under simulated field conditions showed that miracidia moved away from the point of inoculation in non-random fashion and congregated at the margins of the tanks.

3. In a natural habitat, miracidia located and infected caged snails at distances of 33 cm vertically and 106·7 cm horizontally.

4. The pattern of infection was similar in the simulated field and field experiments, but field infection rates were lower.

5. For transmission studies in field habitats, caged laboratorybred snails should be placed at the margin of the habitat to ensure the maximum snail-miracidium interaction.

1. B. glabrata exposed to the sublethal concentrations (0·04 ppm, 0·03 ppm and 0·02 ppm) of TPLA died from the effects of the molluscicide over a period of time. Most of the deaths occurred between the 10th and 35th days after treatment, showing that although TPLA is slow acting, its effect is not continuous but restricted to a limited period of time.

2. 0·01 ppm of TPLA was chosen as a sublethal concentration to study the effect of the molluscicide on the development of S. mansoni in B. glabrata.

3. 240 B. glabrata were infected with S. mansoni, and 40 of these were treated with 0·01 ppm of TPLA 4 days before infection. The remaining 200 were divided into 5 groups of 40 each, one group being maintained as a control and the other four treated 2, 10,15 and 20 days postinfection respectively. Other suitable controls for comparison were also maintained.

4. The infection rate in all groups was high, and comparison with the control showed that there was no significant difference in infection rate between the treated groups and the control group at the 5% level. However, the infection rate in the preinfection treated group was lower than in the control group and significant at the 10% level.

The specimens used for this study were obtained from two collections of helminths sent to the Commonwealth Institute of Helminthology for identification. The first was made by Dr. R. Sachs in his survey of parasitic infestation of wild herbivores in the Serengeti region, Tanzania and the second by Dr. L. D. Fay in a veterinary survey of game animals in Kenya.

1. The four physico-chemical characteristics of water tested— volume, salinity, pH, and turbidity—were each found to affect infection of B. glabrata by S. mansoni miracidia.

2. The rate of infection decreased as the water volume increased from 90·6% at 0·005 litre to 47·5% at 50 litres.

3. The rate of infection decreased as sodium chloride concentration increased, from 78·7% at 0·5 ppm to 2·1% at 4200 ppm. Above 4200 ppm no infection occurred. The activity of the miracidia was affected above 1200 ppm. The snails became non-motile at above 4800 ppm and died within 10 hours at higher concentrations.

In the present goat-dog material great individual variation was observed in the rostellar hooks. The strobila had either 3 or 4 segments in the gravid worms. The position of the genital pore was near the middle in the mature segments and posterior to the middle in the gravid segments. There were more testes anterior (average 27) than posterior (average 18) to the genital pore but they usually extended even behind the vitellaria. The cirrus sac was either elongated or pear shaped. The ovary was bilobed and uterus sacculated.

A linear relationship was found to exist between (1) the reduced weight and length, (2) the number of contained metacercariae and length, (3) the number of metacercariae and reduced weight, (4) the log. oxygen uptake and the log. reduced weight and therefore, (5) between the log. metabolic rate and the log. reduced weight, in the daughter sporocysts of, Microphallus Pygmaeus.

A new species of Dirofilaria, D. (Nochtiella) linstowi n.sp. is described from the subcutaneous tissues of the Grey langur, Presbytis entellus thersites, in Ceylon. The adult worms differ from the hitherto described African and South-east Asian species in several respects, especially spicule size and ratio, arrangement and number of caudal papillae and dimensions of the microfilariae.

The development of the preinfective stages of S. lupi has been described and illustrated and the details of morphology given for the first time.

The sex of the first stage juveniles can be distinguished by locating the position of the genital primordium. On an average, the first stage juveniles measure 0·39 mm. in length and 0·036 mm. in breadth, early second stage 0·78 and 0·044 mm. and the advanced second stage 1·40 mm. and 0·63 mm. respectively. The second stage juveniles obtained from beetles were not infective to dogs.

The cuticle is transversely striated in the region of the head vesicle and shows some longitudinal striations about (0·10 apart. The configuration of the rudimentary mouth capsule and the other head structures are as in the other species of the genus. The length of the head vesicle is 0·082–0·102 and its maximum breadth 0·043–0·055 (Fig. 1.). The oesophagus is 0-371-0-520 long and 0·031–0·043 wide. The nerve ring is situated 0·293–0·313 from the anterior end and the excretory pore is located at the level of the end of the oesophagus or at a short distance in front of it.

1. Laboratory and field trials were carried out to investigate the influence of depth on the infection of B. glabrata by St. Lucian S. mansoni miracidia.

2. In both laboratory and field experiments, miracidia located and infected snails to a depth of 122 cm.

3. The degree of infection seems to be related to the size of a habitat and its water volume.

4. Infection rates were high at the miracidial point of entry where miracidium-snail interaction was maximum and at the water surface where miracidia eventually congregated.

The life cycle of Gastrodiscoidcs hominis has been described using Helicorbis coenosus as the experimental intermediate host and the pig as the definitive host.

The morphology of the miracidium, redia and metacercaria has been described. Data have been furnished on the infection and longevity, of and production of cercariae by the snail host, and the growth and development of the adult-fluke in the definitive host.

Fourteen species of Monogenea (Dactylogyridae) are reported from fish from the Eilat and Suez gulf littoral. The parasites were collected from fish of 12 species (10 families) and include 9 species of the genus Halioirema (Johnston and Tiegs, 1922) (including four new species), two species of Ancyrocephalus Creplin, 1839 and one species of each of the genera: Atherinicus Bychowski and Nagibina, 1969, Diversohamulus Bychowski and Nagibina, 1969 and Placodiscus n.gen.

By means of the standard Ziehl-Neelsen staining technique for eggs in tissue sections S. intercalatum can be differentiated from its sibling species S. haematobium, S. mattheei and S. bovis, since only S. intercalatum egg shells stain red.

This technique could be of great value in Africa in clinical diagnosis and in determining the geographical limits and host specificity of these schistosomes, which may easily be confused on the basis of egg morphology alone.

Both brown trout, Salmo trutta, and rainbow trout, S. gairdneri, from Hanningfield Reservoir, Essex, and adjacent rearing channels, harboured Eubothrium crassum throughout 1968. There was no seasonal cycle of occurrence or maturation of the cestode.

2+ brown trout introduced into the reservoir in the spring acquired heavy infestations during their first summer in the reservoir. Most of these cestodes are apparently lost from fish which have been in the reservoir for a year or more. Possible reasons for this loss are discussed.

Antigens prepared from adult worms and microfilariae of Loa loa were used for an assessment of the sensitivity and specificity in diagnosis of double immuno-diffusion in agar gel, haemagglutination and fluorescent antibody tests.

Both antigens formed a broad band which moved slowly towards the cathode on electrophoresis, and each antigen separated into two protein fractions when passed through Sephadex G-200.

Both precipitating and non-precipitating antibodies were detected in sera from Loa loa patients. The haemagglutination test and fluorescent antibody test were sensitive in detecting Loa loa antibodies and would be of diagnostic value, but the double diffusion test in agar-gel was insensitive and would have a limited value in loiasis diagnosis.