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.

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.

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.

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.

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.