The pathological effects of adult O. cervicalis on the ligamentum nuchae of infected horses are of minor importance and although small calcified or caseous nodules are sometimes found, chronic inflammatory conditions (poll-evil or fistulous withers) were not seen in the examination of over 120 infected horses. Pathological conditions due to microfilariae, in either the skin or the eyes of the host, were also of little importance and no reactions were seen which could definitely be attributed to the parasite. The only lesions seen on the abdominal skin of an infected horse, closely resembled the lesions of sweet itch which is not connected with the parasite but is probably due to a hypersensitivity reaction to the bites of the midge Culicoides pulicaris.

The present paper describes the size range of Ternidens deminutus from human and baboon hosts in Rhodesia and discusses the possible reasons for the differences noted.

Using transmitted light and the scanning electron microscope, the external morphology of T. deminutus has been re-studied and compared to investigations by other authors using transmitted light microscopy alone.

The paper also illustrates the value of the scanning electron microscope in morphological studies in helminthology, especially when used in conjunction with the light microscope, to give an excellent three-dimensional picture of the species under investigation.

It is intended to follow this work with further studies on the anatomy, histology, ultrastructure and histochemistry of Ternidens deminutus.

A detailed description is given of a filarial parasite, Breinlia booliati sp. n. from the thoracic cavity of the Malayan rat, Rattus sabanus (Thos.) trapped in Malaysia.

The development of the larvae of Breinlia booliati a new filarial parasite of the forest rat Rattus sabanus in Aedes togoi is described. Complete larval development to the infective stage occurred in the fat body of the head, the thorax, and especially the abdomen of the mosquito. The first moult occurs at 7 days and the second at 11 days. As the larvae grow very rapidly in length, the parts of the parasitized fat body cells which harbour the developing larvae take on a syncytial appearance. By the 11th day, the larvae move out from the fat body into the haemocoele. The infective forms are found in the proboscis at the 12th day after the infecting blood meal.

Heterakis gallinarum known to transmit Histomonas meleagridis were transferred when 10 and 14 days old from chicken to chicken to chicken, chicken to chicken to turkey, and in other combinations of these 2 hosts. Results were compared throughout with those attending single transfers of worms and no transfer at all. H. meleagridis was liberated and became detectable in as little as 24 hours in some recipient birds. Recipient chickens some times developed infections with H. meleagridis even though the protozoan had never been found in either the original donors of 10-day larvae or donors of 14-day worms.

Recovery of mature Heterakis gallinarum from recipients of 10-day larvae was about 1 1/2 times that from birds in which heterakids developed from hatching to maturity without being disturbed. Transferred worms were 10–17% larger at maturity, suggesting that a single transfer at 10 days was less detrimental than uninterrupted development in the partially immunized bird. Recovery of H. gallinarum from turkey recipients of 10-day larvae equalled that from comparable chicken recipients, but turkey recipients of 14-day heterakids yielded fewer heterakids than did their chicken counterparts, whether 1 or 2 transfers had been made.

Seven calves, 5 sheep, 2 goats and one buffalo calf were exposed to S. bovis cercariae in the laboratory. The prepatent period varied from 44–45 days in calves, 47–50 days in sheep to 47–48 days in goats. The recovery rate of adult worms was 62.1% in calves, 41.4% in sheep and 67.3% in goats. The infection rates were much higher than those obtained by previous workers, possibly because of a superior technique. One buffalo calf was exposed to S. bovis cercariae but showed no signs of infection.

The mean daily egg output per gram of faeces was 75 in calves, 60 in sheep and 75 in goats. The daily egg output in the faeces per individual female worm was 106 in calves, 52 in sheep and 48 in goats at 9 weeks after exposure to cercariae. The number of eggs passed in the faeces decreased in calves and increased in sheep as the duration of infection was prolonged.

O. turkestanicum infection was found to be uniformly distributed in the northern and central parts of Khuzestan (cattle, 30%, sheep, 15%; goats, 7% and buffaloes, 2%). In the southern part of Khuzestan the infection rate was very low. A new technique was devised for exposing large animals by leg immersion in a cercarial suspension in a polythene bag and good infections were obtained by this method. The prepatent period of O. turkestanicum infection in different types of animals varied from 43–46 days. The recovery rates of adult worms were 37.6% in calves, 33.9% in sheep, 22.5% in goats and 9.6% in a buffalo. O. turkestanicum produced a milder pathological response in ruminants than did S. bovis, but is nevertheless of considerable economic importance in Khuzestan.

A defined medium is described as a basis for in vitro culture work with larval Fasciola hepatica. This medium, termed BCM, can be quickly made up by using a system of stock solutions. BCM contains inorganic salts, glucose, amino acids, vitamins and antibiotics, but no lipid or proteins. Rediae can be dissected from infected snails for culture, but many appear to be contaminated with bacteria. Large rediae cannot survive in BCM but free immature cercariae can complete their final maturation in vitro. This final maturation, from the 30th to the 35th day after miracidial penetration of donor snails, includes tail growth and appearance of body pigmentation. Cercariae matured in vitro encyst successfully when transferred from BCM to water. Small rediae survive in BCM for 5 days, but show no growth or development measured as dry weight and total nitrogen.

The conglutinating complement absorption test (CCAT) has been used to detect Cysticercus tenuicollis (Taenia hydatigena cysticercus) infection in sheep and goats. Sera from naturally infected sheep and goats showing a titre above 1:40 were considered positive for cysticercosis. Experimentally infected lambs gave a higher antibody response than sheep and goats.

Since the discovery by Shapiro and Zwarenstein (1934) that females of Xenopus laevis (Daudin, 1802) respond to hormones present in the urine of pregnant women, this species of amphibian has proved to be a useful experimental animal. It is easily kept in captivity and can be reared through all its developmental stages without difficulty.

This species, the clawed toad or platanna, is commonly used in South African Universities as a type for first year dissection. This has given the opportunity to check large numbers of specimens for the more obvious parasites, i.e. those which live in the gallbladder, the urinary bladder, the peritoneal cavity and the pericardial cavity. A similar large scale survey of intraintestinal parasites has not been feasible, although many alimentary canals have been searched for parasites.