Researches involving dilution egg-counts, recently carried out by members of the staff of this Institute, have shown that the error variance, i.e. that between parallel counts, approximates more or less closely to the mean count. The following examples illustrate this point:—

The counts were all made by the same technique, and it is fair to total them in order to observe the average effect. This agreement between variance (or mean square) and mean is a feature of the Poisson distribution, and it has been assumed that dilution counts are in fact distributed according to the terms of that series, in all cases where the technique is adequate. Reasonable agreement between mean and error variance becomes, indeed, a criterion of the accuracy of the sampling technique. The purpose of the present note is to enquire a little further into the theoretical basis of this assumption, doubts having arisen as to whether high counts (say, up to 100) can be expected to conform to the Poisson series.

The essence of the McMaster (Gordon & Whitlock) technique is that one counts the eggs lying under a centimetre square engraved on a coverglass which is supported 0·15 cm. above a slide, i.e. the eggs contained in 0·15 cc. of faecal suspension. Since the suspending liquid is a half-saturated solution of salt, the eggs float up into one optical plane immediately below the coverglass, this making for ease in counting.

The earlier work of this Institute on phenothiazine in lambs (Peters et al, 1941; J. Leiper et al, 1941) using egg-counts, worm-counts, and lamb-weights as criteria of anthelmintic efficacy, has revealed conflicting results as between one criterion and another. Thus, the lowest dosage rate used (0·15 gm. per Kg.) led to a reduction in the egg-count, whilst even the highest rate (1 gm. per Kg.) led to no reduction in the worm-count: by an irony of chance the worm-counts were lowest in the untreated controls in both experiments. In the first experiment weights were not affected by the drug, and in the second the only significant effect was a set-back in those lambs given tablets. Numerous other workers have reported increased weights due to the drug, in long-term experiments; ours were too short in duration to show such increases, yet the danger of reinfestation precluded any extension of the time, the lambs being kept outside on infective pastures. The most obvious explanation of the egg- and worm-count results appears to be that the drug has a temporary inhibiting effect on egg-laying, which would presumably return to normal in a few weeks; but here again a prolonged experiment increases the liability to reinfestation.

These being the relevant circumstances, the present experiment was designed to take account of them in the following ways. In the first place the lambs were kept inside throughout the experiment, their stalls being cleaned out thoroughly twice a week to obviate reinfestation.

A total dose of 30 gm. of phenothiazine, given as tablets in one dose of 15 gm. and three of 5 gm. to three goats and six sheep known to be worm-free, had no effect on the weights of the animals in comparison with equal numbers of worm-free controls, over a period of 15 weeks from the first dose.

It is concluded that weights can validly be used as a criterion of anthelmintic efficacy; they not only constitute an obvious economic criterion, but also are statistically more sensitive than egg-counts when subjected to analysis of covariance.

Hook dimensions of Multiceps glomeratus show that the hooks are capable of reaching full adult size in the coenurus stage.

The available material showed that M. serialis hooks were slightly larger than those of M. glomeratus in the adult stage; in the coenurus stage the differences were not significant.

Statistically, the dimensions measuring the length of the blade of the hook are the most satisfactory.

There are significantly large variances in most cystic hook dimensions from one cyst to another, and from one scolex to another within a single cyst, but not from one group of scolices to another. It follows that in biometric work it is important to sample several scolices from each cyst, and several cysts of any one species, but that groups can be disregarded.

The variability of most hook measurements is in the region of 5%; i.e. the standard deviation is about 5% of the mean dimension.

The danger of extensive generalisation from limited data should be guarded against. Thus, while the species variance was significantly larger than the cyst variance in the case of adult hooks in the material available, it is quite possible that this would no longer have been the case if material from other sources had been available.

In the spring of 1941 a male patient died at Peterborough and the autopsy which followed showed that death was due to pontine haemorrhages. As the brain also carried a coenurus, it was submitted to me for further examination. I am much indebted to Dr. David Fulton, M.D., M.R.C.S., L.R.C.P., pathologist and physician to the Peterborough and District Memorial Hospital, and to Dr. L. P. Garrod, M.R.C.S., F.R.C.P., pathologist to St. Bartholomew's Hospital, London, through whose kindness and good offices this interesting specimen was made available to me.

The changes in protein digestion, crude fibre digestion and the chief urinary constituents found in four rats after experimental infection with Trichinella spiralis are detailed.

Diarrhoea and anorexia occurred during the period 8 to 12 days after infection when protein digestion fell to its lowest point. It is suggested that this was due to antiproteases secreted by the adult parasites and to mechanical damage in the intestinal mucosa caused by their movements.

Urinary N rose immediately after infection in “non-resistant” rats. This was followed by a period of decreased N output after which the excretion rate rose steeply.

The urea output also rose immediately after infection in “non-resistant” rats. During the period 4 to 12 days from the time of infection urea excretion fell. Thereafter there was a great increase in its rate of output. Most of these changes have been attributed to toxins elaborated by the adult parasites for massive larval invasion of the tissues probably did not occur till after the experiments were terminated.

Ammonia excretion rose as urinary urea decreased. The fall in urea N was not compensated by the rise in ammonia N + the fall in dietary N intake. The ammonia output returned rapidly to normal suggesting that the excess ammonia was not produced in response to acidosis when the urea excretion rate rose.

Creatine excretion showed a marked fall during the period 4 to 12 days after infection. Urinary creatine and creatinine rose steeply following this period. Possible reasons for these variations are discussed.

In the body cavity of a female specimen of the fly, Sepsis cynipsea L., (Diptera-Cyclorrhapha), caught at this Institute in August, 1930, the writer found eight adult nematode parasites; 3 females and 5 males. The fly was dissected in Ringer's solution in which the worms became actively motile when set free from the host. At the time of dissection it was seen that the fly's ovaries were in an undeveloped state and there is no doubt that this was due to the presence of the parasites within the body cavity. Beyond noting the fact that the worms seemed to be of a mermithid type they were not investigated further at the time but were fixed in hot 70% glycerine alcohol, to which a trace of Nile Blue sulphate solution was added, and were set aside. Although a good number of the flies were dissected during the month of-August no other example was found to be infected with this species of nematode and, as the worms have not been found again since 1930 in casual specimens of the fly captured and dissected here, it seems desirable to describe them since they appear to be new to science. Structurally they bear some resemblance both to Aproctonema entomophagum Keilin, 1917 and to Tetradonema plicans Cobb, 1919 but differ from these species in several anatomical features. Their systematic relationships are discussed in detail later on.

Debray and Maupas (1896) described a disease of broad beans, Vicia Faba L., occurring in and around Algiers, N. Africa, caused by the stem eelworm, Anguillulina dipsaci, the adults of which were considerably larger than from any other host plant attacked by this species; the females being 1·758 mm. to 2·216 mm., and the males 1·716 mm. to 2·016 mm. long. As far as the writer is aware, from the time their paper appeared to the present time no further record of such giant forms of A. dipsaci has been published. During the past few years the writer has encountered similar large forms in diseased broad bean stems, first in material originating in Portugal and on two later occasions in bean plants grown under ordinary field conditions in this country, and it seems desirable to put on record a short account of his observations.

The occurrence of the chrysanthemum eelworm, Aphelenchoides ritzema-bosi (Schwartz, 1911), in an unusual situation, namely within the tissues of tomato fruits, calls for brief report since, though well known as a leaf parasite of a good number of plants, it has not, to our knowledge, been reported previously from a fruit.

Towards the end of October, one of us (S.H.B.) visited a grower who complained of having a number of tomato fruits from which the calyx tissue came away at the slightest touch. These fruits then rotted deeply towards the centre. Two such fruits were taken from the store for examination in the laboratory. One of them was attacked by the fungus Didymella Lycopersici whilst the other was found to contain eelworms. This fruit was sent by S.H.B. to T.G. with a request for a determination of the species of eelworm present and an opinion on whether it was a parasitic species or not.

On receipt of the fruit the senior author cut it in two by a cut passing along the longitudinal axis from the calyx region and through the central fleshy placenta. It was then seen that the discoloured diseased area was about ¼ in. deep by about ⅝ in. broad and occupied much of the solid fleshy base of the fruit. On teasing up a small portion of the diseased tissues in water and examining under the binocular microscope, considerable numbers of small eelworms were found together with numerous eggs and larvae in various stages of growth.