By feeding infected flesh to experimental animals, and examining the stomach contents of the latter at varying periods after feeding, various workers have shown that Trichinella larvae are released from their cysts within one or two hours after reaching the stomach of the experimental host. (Bugge, 1934, Heller, 1933, 1934, Kreis, 1937.) The actual release of the larvae from the cysts has not been followed, though Kreis (1937) on the basis of the appearance of stained cysts recovered a short time after ingestion, suggests that the larvae are released not only by the action of the gastric juice of the host, but also as a result of secretory activity by the larvae themselves within the cysts.

Field observations made in 1935 on a potato crop growing on what was thought to be potato sick land in Bedfordshire seemed to indicate that eelworm damage due to Heterodera schachtii was less pronounced where maize had been the previous crop than in other cases. As particulars of the history of this piece of ground were not available, detailed observations were not made, but it was decided that it might be valuable to carry out experiments with maize to determine whether this plant had any effect on eelworm cysts. Other members of the natural order Gramineae have been shown by Triffitt to stimulate the larvae of H. schachtii to hatch from the cysts, and it was thought that maize might have a similar effect.

Preliminary experiments were carried out during 1935, on the possible application of certain chemical substances to the problem of controlling “potato-sickness.” The results were published in two papers by Hurst & Triffitt (1935, i, ii) and it was shown that calcium cyanamide and ferric oxide were deserving of further trials on a larger scale. Field experiments were devised and carried out during 1936 in various parts of the country, and the results will be communicated when these are available. In the meantime the small-scale experiments were continued and are described below.

The only account we have of this species of nematode, which is apparently parasitic in the bark of mahogany trees in Barbados, British West Indies, is that given by Cobb (1920). The material forming the basis of his investigations consisted of specimens preserved in formalin which had been sent to him from the Department of Agriculture, Barbados. His description of the adult worms, while being very detailed in certain particulars, gives little information in regard to other anatomical features. In addition, the drawings illustrating his paper show only two views of the head region and the male tail in ventral and lateral aspect. During the past twelve months the writer has had an opportunity of making some observations on this species. A piece of diseased mahogany bark was received in April, 1936 from the Director of the Imperial Mycological Institute, Kew, to whom it had been sent from the Department of Agriculture, Barbados. The bark and scrapings from it were in a preserving fluid of unknown composition and in the sediment at the bottom of the jar numbers of adult worms of both sexes were present. Several of these were picked out, washed in water and transferred to weak glycerine. The capsule containing them was set aside for the glycerine to become concentrated and the worms were finally mounted in this medium.

It is a well known fact that Heterodera schachtii in the brown cyst stage can survive in soil for several years in the absence of host plants. Fuchs found living contents in five-year old cysts of the beet strain of this nematode, while eight-year old cysts of the potato strain have been found by the writer still to be infective to the host plant. Thus, the starving out of this parasite by withholding susceptible crops would appear to be impracticable.

Although it may be objected that the present paper deals with a limited population in a circumscribed area, the conclusions drawn are in the main applicable to any zone of endemic Bilharzial infestation. The numbers examined form a considerable series, and the distribution and age and seasonal incidence of the contrasting infections are of some interest. A personal relation with those infected has been, and still is, maintained.

This communication is concerned with the field trials of substances which in previous small-scale experiments had shown promise of controlling “potatò-sickness” when they were mixed with infected soil.

In the investigation of plant material infested with parasitic and related nematodes various methods are available. One often has recourse to the teasing apart of affected tissues in water with the liberation of the contained organisms or the latter may be obtained by soaking the material in a Baermann funnel. It is frequently desirable, however, to determine the actual presence and location of nematodes in the host tissues without recourse to teasing and for this purpose some appropriate method of staining is necessary such that the nematodes are suitably coloured whilst the tissues of the host are coloured but little or not at all and thus permit the passage of light after the usual processes of dehydration and clearing have been carried out.

“Tulip-Root” in oats caused by the stem eelworm, Anguillulina dipsaci, is of widespread occurrence in Great Britain, annually effecting much damage to oat crops which results in diminished yields of grain. At this Institute the disease has been under investigation for some years and during the seasons 1935, '36 and '37 tests have been carried out on the susceptibility to it of a number of different oat varieties. An outcome of some practical importance has resulted from this work in that it has been found that two varieties of winter oats have, for three seasons, proved resistant to attack though grown under the same conditions and subject to the same risk of invasion by the parasite as other varieties which have proved susceptible to attack. These two varieties have consistently manifested no symptoms of disease during the three seasons and on microscopic examination have been found to harbour very few examples of the parasite whereas susceptible varieties have shown the characteristic symptoms of disease in stunted growth, greatly swollen discoloured leafbases and their tissues have harboured large numbers of the parasite. The purpose of the present paper is to put these facts on record and to give some account of the investigations out of which they have arisen.

The investigations described in this paper are in part a continuation of those described by Carroll and McMahon in a previous paper published in 1935. The previous paper demonstrated the fact that the root excretion of potatoes growing in recently sterilized soil does not possess the power of inducing the hatching of eelworm eggs in the normal manner. It was shown that when eelworm cysts were placed in soil leaching (containing potato root excretion) obtained from pots of very recently sterilized soil growing potatoes practically no hatch of the eggs in these cysts took place until after the lapse of about thirty days. It was further indicated that this interval of time which elapses before hatching commences diminishes according as the period between time of sterilization of the soil and time of obtaining soil leaching for hatching experiment increases.

1. The results of post-mortem examinations of 590 dogs and 185 cats in Shanghai are reported.

2. 88% of the dogs and 97% of the cats were infected with one or more species of helminthic parasite. The cats tended to harbour a larger number of species per animal than the dogs.

3. Infections with trematodes were very common, especially Clonorchis sinensis which was present in 79% of the cats.

4. There was a comparatively low incidence of infection with Ancylostoma caninum.

5. Prohemistomum industrium, and Echinostoma ilocanum, rare parasites of the dog, occurred.

6. The following parasites are recorded in their hosts for the first time in China.

1. Chlamydonema praeputialis in the dog.

2. Cylicospirura subaequalis in the cat.

3. Metorchis albidus as a natural infection in the dog.

Potato tubers infected with Heterodera marioni having been received at this Institute, it was decided to attempt to infect a small field plot with this eelworm for experimental purposes. The tubers were planted in the plot but the infection never became established. This was thought to be due to the heavy nature of the soil, since H. marioni has been recorded as a field parasite in Britain (Triffitt, 1931), and it is therefore unlikely that climatic conditions were the cause of its failure to become established in this instance. In order to verify this, and to find out how long this parasite can survive in soil in the absence of a host, the following experiment was carried out.

A turkey poult sent for post-mortem examination to the Veterinary Research Division, Ministry of Agriculture, Northern Ireland, was found to be suffering from a very heavy infection of a small fluke.

Although the “potato-sickness” associated with the nematode Heterodera schachtii has been the subject of a good deal of investigation in Britain during the past twelve years, the only practical method of control so far devised is the adoption of a well-planned crop rotation in which potatoes are omitted for several years. The limitation of a general application of this method to the thousands of acres of land infected with this eelworm disease but otherwise admirably suited for the growing of potatoes has led to insistent demands for further study into chemical treatment of affected soil. In the present investigation, comparative control trials of soil treatment by certain chemical substances were carried out on land known to be thoroughly “potato-sick” and the last potato crop grown in it had been a failure. Most of the experimental treatments had already shown in other field experiments some measure of protection from “potato-sickness,” at least, judging by the healthier appearance of the foliage and increase in yield of crop. Although the results of previous experience indicated that there was a positive association between application of these various soil dressings and intensity of disease, it was felt that a more accurate computation of the latter, by measuring the eelworm cyst content of the soil, was desirable before any definite conclusion might be drawn.

From time to time attempts have been made to control the spread of sclerostome larvae by treating the manure before use on the pastures or by mechanical means such as ploughing the land to bury the larvae. Various chemicals have been used, including artificial manures and animal waste products. Lucker (1936) buried larvae at varying depths in soils of different quality and measured the percentage that appeared on the surface during periods up to six weeks. Clay soils were almost a complete barrier to vertical migration whereas sandy soils and coarse sand permitted migration, during a period of 3–8 weeks, of appreciable numbers when buried 1–6 inches. He suggests from this evidence that ploughing the land would bury the larvae and therefore reduce the number of infective larvae available to the stock. It would seem to the writer, however, that there is a fallacy in this argument. Ploughing the land would turn the soil over but, even if a plough press were used, many fissures would be left which might form an easier channel for migration to the surface. Infective larvae readily accomplish horizontal migration and the possibility of lateral migration along the overturned turf and up the fissures must not be overlooked. The action of frost and the presence of roots in the overturned sod would possibly be other factors in encouraging vertical migration, not to mention the subsequent preparation of the land required before seeding down again for permanent pasture.

During the past two or three years the writer has had an opportunity of making observations on certain plants which are new hosts of the stem eelworm, Anguillulina dipsaci. In the present paper four such plants are dealt with, three of which are cultivated garden plants and one a common weed. Of the garden plants, one is a useful food plant, namely the parsnip (Pastinaca sativa L.) and the other two are Primulas, namely Primula pulverulenta Duthie and P. polyantha Mill, (polyanthus primrose). The weed is swine-cress or wart-cress (Coronopus Ruellii All., syn. Senebeira Coronopus Poir.)

In Australia this disease has occurred in many oxen on sewage farms and despite the economic loss involved, the farms have been prevented from raising cattle for human consumption. It has been claimed that this policy was adopted because of the risk to man of infestation with Taenia saginata. The object of this paper is to show that this economic waste is quite unnecessary, for cattle can be readily immunized against the disease so that there is no risk of Taenia saginata infestation in man from eating beef from such cattle.

In the routine examination of stray dogs in a country area near Shanghai, a large percentage were found to be infected with Dirofilaria immitis. The microfilariae were easily found in blood films stained with Leishman's or Giemsa's stain. In some cases only a moderately heavy infection was found, but in some hyper-infection was present. (See fig.)

In Britain, the year 1937 is likely to be memorable in the history of cultivation of many species and varieties of plants belonging to the genus Primula, as witnessing, for the first time, attacks of great severity by the nematode, Anguillulina dipsaci in a number of plantations of Primulas, reducing the vitality of the plants wherever it occurred, and in many instances causing complete destruction of certain species. The plants classed as members of the Candelabra Section, which includes some of the finest and most extensively grown species and varieties in the whole genus, proved particularly susceptible but, while members of many of the other Sections of Primulas did not escape attack, the injury inflicted was not usually of such high order of severity.

The species Bucephalopsis karvei n. sp. has been described in detail and separated from the allied species. A survey of the work on Bucephalidæ has been given and the species B. magnum, B. confusus and B. minimus have been considered to be synonyms of B. garui. A key to the existing valid species of Bucephalopsis has been given.

The genus Catoptroides has been merged into the synonymy of Phyllodistomum and arguments for so doing have been advanced. Revised diagnosis of Phyllodistomum has been given.

Phyllodistomum shandrai n. sp. has been described and separated from the allied species. P. sp. has been briefly described. Key to the species of Phyllodistomum has been given.

Paramphistomum maplestoni n. sp. and P. cuonum n. sp., have been described and separated from the allied species P. orthocœlium. A few observations on P. sp. from a wild cat and Diplodiscus amphichrus from Rana tigrina have been recorded. Paramphistomum cervi, P. sp., Cotylophoron orientalis and Gastrothylax crumenifer have been recorded from neelgai, hog deer and sable antelope respectively.

Helostomatis sakrei n. sp. has been described and separated from H. helostomatis. A revised diagnosis of Helostomatis has been given.

Neocladorchis poonaensis n.g., n. sp. has been described. The new genus Neocladorchis has been defined and separated from the allied genera.