During the past nine years the writer has collected many helminths from the gastro-intestinal tract of various antelopes in Northern Rhodesia.

Amongst the collected material are oesophagostomes from the Puku (Adenota vardoni), the Red Lechwe (Onotragus leche), the Duiker (Cephalophus natalensis), the Kudu (Strepsiceros strepsiceros) and the Roan Antelope (Hippotragus equinus).

Three methods of differentiating the various strains of Heterodera schachtii are tried out in an attempt to find a quick means of identifying the strains.

Infection experiments using possible host plants, though they are the final test of strain, require careful handling and take some weeks to carry out. In a limited number of such experiments a strain of eelworm occurring on wild clovers appears to be distinct from the pea, oat and beet strains. A strain parasitic on Myosotis appears to be distinct from the clover strain.

A method of recovering cysts from soils of not more than 10% water content is described. The method is continuous and the yield from it is only slightly lower than that from the dry flotation of soil. The yield was found to contain a slightly lower percentage of full cysts than that obtained by dry flotation but this drop was not considered sufficiently great to justify the drying of soil in large quantities. Quantities of soil in the neighbourhood of 1 cwt. can be handled continuously in a matter of two hours.

Since the publication of the writer's (1932) paper on the nematode genus Anguillulina, opportunities have occurred from time to time for making further observations on the morphology and anatomy of some of the species of the genus found associated with the roots of plants. Certain of them are parasitic in roots, at least during part of their life, at other times occurring free in the soil. Others have not been found within roots but have been obtained only in water extracts of turf and their exact relation to the roots of plants is at present undetermined.

The migrations of infective larvae of sheep and horse Strongyles have been studied by various workers, principally in relation to their behaviour in faeces or in different types of soil. (Bruns, 1937 and Lucker, 1938). The factors affecting the extent and nature of the migrations of certain infective larvae on to grass have also received attention (Rogers, 1940). A knowledge of the behaviour of larvae both in soil and on grass is very necessary if control methods either by chemicals or by controlled pasturing are to be effective. The present paper, however, describes an attempt to study the fundamental behaviour of these larvae in the laboratory, in the hope of obtaining results of practical value or of filling up certain gaps in our knowledge of them. A simple technique was sought, whereby the migrations of the larvae could be studied in the laboratory under different conditions, and is described herein.

Laboratory experiments have shown that cysts of the eelworm Heterodera schachtii adhering to seed potato tubers are killed by immersion of the tubers for 6 hours in 5% formalin solution (Franklin 1939). Further experiments were designed to determine what effect such treatment has on the seed tubers and on the resulting crop.

Evidence is put forward to show that eggs of helminth parasites are being constantly re-introduced to land and transferred from one pasture to another. In this way land which has not previously carried poultry for years may yet carry viable eggs which can, and do infect chickens when they are introduced to such runs. The starling and rook are probably important transmitting agents as these congregate among poultry at feeding times. Rabbits and other small rodents may also be carriers but no evidence for this has been looked for yet. Young poultry stock may also become infected with helminths which are normally parasites of wild birds but such parasites, except one Acanthocephalan, have not yet been recovered from or transmitted to older birds experimentally.

In 1925 Chapin reviewed the genera Syngamus and Cyathostoma and in the review described a new species of Syngamus which he had obtained from the American Crow, Corvus brachyrhynchos: this, he called Syngamus gracilis. It had been found in a bird from the Zoological Gardens at Philadelphia. He was of the opinion that this species had probably been recovered before from the American Crow but that its specificity had not been recognised. He assumes, in fact, that some if not all of the records of the occurrence of S. trachea in this species of host, and by inference probably in other Corvidae also, are incorrect and that S. gracilis is the species found. He bases this assumption on the physiological reactions of the parasite. It is a well known fact that S. trachea does not establish itself well in chickens and can in fact only reach maturity in young or very sick birds. The turkey is generally assumed to be the natural host of this helminth and Chapin is of the opinion that if S. trachea cannot establish itself satisfactorily in the chicken, then it is highly improbable that it can do so in the crow. For the chicken and the turkey are closely related phylogenetically, both being gallinaceous birds while the crow belongs to the Corvidae, which has no near kinship with the Galliformes.

At known periods the infectivity, fat content and activity of larvae of Haemonchus contortus aged at 7°C, 24°C. and 37°C, were examined.

The relationship between fat content, activity and infectivity was found to be fairly close in rapidly aged larvae. In slowly aged larvae the infectivity fell more rapidly than the other factors.

The genus Heterodera comprises three species, the root-knot nematode, H. marioni (Cornu 1879) Goodey 1932, and the two species in which cysts are produced. These are, H. schachtii Schmidt 1871, which is associated with disease in potatoes, sugar beet, cereals, peas and some other crops, and H. punctata Thorne 1928, which has caused disease of wheat in Canada, and has been found in this country infesting a common grass Agrostis stolonifera L.

The structure of the normal coenurus of M. glomeratus is described and some observations have been made on its powers of budding and vegetative growth and reproduction. It is suggested that only a small area of the cyst has the power of growth and development and that budding and daughter cyst formation is an action which attempts to stave off old age and sterility. It has been found possible to cause new growths and infections by the transplantation of certain elements to new hosts. Some remarks are made on the occurrence of abnormalities in a coenurus cyst.

Infections with Coenurus glomeratus, which has been reported from West Africa, have been accomplished successfully in the mouse, in the rabbit and gerbille.

Such coenuri produced infections of adult cestodes in the dog but not in the cat.

The coenurus is described from each intermediate host.

The examination of Strongylus edentatus and S. vulgaris revealed that these parasites ingest the hosts' blood and that haematin is the result of the digestion of haemoglobin. The amounts of blood necessary to form the quantities recorded as being present in the parasites' intestines have been calculated.

The intestines and their contents taken from several lots of Strongylus edentatus and S. vulgaris have been analysed and the amounts of certain metals and sulphur present have been estimated.

Zinc was found to be the most plentiful metal present, reaching a maximum of 0·58 mgs. per worm. Copper, silver and iron were the other metals recorded.

A set of 275 egg-counts, made by a modification of Stoll's dilution-technique and involving 11 series of 25 counts each (each series having a different mean), was found to be distributed in approximate agreement with the Poisson distribution. Although from its nature not normal in form, it showed no significant departure from the corresponding normal curve.

Amylolytic enzymes have been extracted from the intestines and contents of Strongylus edentatus and Ascaris lumbricoides (pig strain). The saccharogenic and amyloclastic actions of these enzymes have been examined in relation to the salts present and hydrogen ion concentration.