Amongst biological strains or races of the.stem eelworm, Anguillulina dipsaci, some are comparatively polyphagous and are capable of causing disease in a number of different host plants whilst others are restricted to one or two hosts. The strain causing “ tulip root” in oats is usually regarded as a restricted one being Confined to oats or, as in Yorkshire, to oats and beans, in which infection takes place in the seedling stage and persists during the greater part of the life of the plant. Whether the parasite will attack other agricultural plants is a matter of some practical importance and since in a crop rotation a seeds mixture for ley production may follow oats, it was decided to test whether the parasite would infect plants comprising a typical seeds mixture. It was also hoped to determine whether any of the grasses or clovers would be more or less permanently affected and thus serve as reservoir hosts for the parasite and so enable it to tide over the period between successive oat crops. The present paper deals with pot experiments set up to test this matter as a result of which it has been found that the oat strain of the parasite is capable of causing serious injury to the young seedlings of a number of grasses and clovers of a seeds mixture.

In a previous paper, Peters & J. Leiper (1940) pleaded that, in anthelmintic experiments, the statistical problem of variation should be considered, not only so as to assess the significance of treatment differences after the results have come to hand, but also with a view to the prior construction of an experimental design capable of giving reliable answers to the questions posed. Reference was made to the “Enormous expenditure of time, labour and money” on anthelmintic experiments, the results of which usually remain undigested and of unknown significance.

While the paper was passing through the press a symposium on phenothiazine as an anthelmintic, led and summarized by Taylor & Sanderson (1940), was published in the Veterinary Record. The symposium deals with “Work carried out in various parts of the country and co-ordinated through the Agricultural Research Council” it covers some 150 horses, 300 to 400 sheep, 70 to 80 goats, and a few cattle, pigs, and dogs. The drug was found to be remarkably efficient against horse strongyles and the stomach-worms of ruminants, and in varying degree less efficient against other worms.

Extensive tables of egg-counts, worm-counts, and weights of animals are published in the symposium. It was usual to count eggs or weigh animals once before treatment and several times afterwards. The repeated after-treatment determinations are made in order to detect a general trend in egg-counts or weights: in other words there is no attempt to measure and make allowance for the very considerable upand- down variation from day to day.

In an experiment previously reported (1941) we were able to show little anthelmintic effect against the gastro-intestinal nematodes of sheep after using phenothiazine powder in single doses up to 0·3 gm. per Kg. body weight. In view of our experience and its contrast with that of many" other workers, we felt it desirable to test a much larger dose, to compare it with another brand of the drug, and (because of the very large variation in worm burden from lamb to lamb) to use not less than four lambs in each treatment group.

Accordingly, 12 lambs from a flock known to be naturally infested were purchased last November, and these were divided at random into three groups as follows: A, untreated controls; B, given compressed 5 gm. tablets of phenothiazine (recently placed on the market by a well-known firm) at the rate of 5 gm. per 5 Kg. body weight; and C, given phenothiazine powder in water as a drench, at the same dosage rate, with the addition to each dose of 1 gm. sodium glycocholate as a wetting agent. This powder was from the same batch as that used in our previous experiment. In each case the full amount was given as a single dose.

The same three criteria of efficacy were used as before: three eggcountings and lamb-weighings before and after treatment, and post mortem worm-counts. Eggs were counted by the same modified McMaster technique, the individual counts representing the eggs in 0·005 gm. of faeces, but on this occasion only three cells were counted per sheep per day.

Enzymes hydrolysing olive oil and ethyl butyrate (probably lipases and esterases) have been extracted from the intestines of Strongylus edentatus and Ascaris lumbricoides (pig strain).

Maximum enzyme activity was obtained at pH 8·0.

A. lumbricoides enzymes were assisted by sodium glycocholate. Sodium taurocholate had a retarding effect on the enzymes from both parasites.

Enzymes extracted from A. lumbricoides were activated by the presence of NaHCO3 solutions whereas S. edentatus enzymes were not activated by this salt.

Esterase action, relative to lipase action, was 2½ times greater in S. edentatus than in A. lumbricoides.

Tryptic-like enzymes have been extracted from the intestines and intestinal contents of Ascarts lumbricoides and Strongylus edentatus. The action of these enzymes, in relation to hydrogen ion concentration, has been examined.

The parasite trypsins resembled pancreatic trypsin in that the relative production of “free acid” and “formaldehyde acid” was similar, but though acting only on the alkaline side of the isoelectric points of the substrate proteins, optimum action on gelatin, blood-albumin and casein was obtained at pH 6·2.

The amount of protease extracted from a given weight of S. edentatus tissue was far greater than that from a similar amount of A. lumbricoides. Thus Strongylus digested 4·9 to 8·3 times as much gelatin, 12·5 to 40·9 times as much casein and 2·5 to 5·2 times as much blood-albumin as Ascaris.

Spectroscopic examination of the process of digestion of oxyhaemoglobin showed, first, the formation of reduced haemoglobin and then the formation of haematin. These changes took place most rapidly at higher hydrogen ion concentrations.