The question as to whether Ascaris from the pig may be transmitted to man, and its converse, have long been recognised as being of considerable public health importance. Hitherto the evidence, both epidemiological and experimental, is somewhat in favour of the belief that human Ascaris and Ascaris from the pig are not interchangeable as to their respective hosts. Experimental evidence in support of this was supplied in 1922 by Koino, who swallowed a large number of embryonated eggs from the pig form, and although severe pneumonic symptoms were set up by the migrating larvæ, the latter did not complete their development, and no intestinal infestation followed. A similar negative result was obtained by Payne, Ackert and Hartman (1925), from infection experiments performed on themselves and on a rhesus monkey; they also fed large numbers of human Ascaris eggs to pigs but without success. Some epidemiological evidence has also been furnished by these workers, for they indicated that although in Trinidad and Arouca the circumstances were favourable for reciprocal infection, yet the incidence of Ascaris in man and pigs in these regions in no way suggested that such a condition of affairs obtained.

About the middle of June, 1931, the writer received from the Ministry of Agriculture Plant Pathological Laboratory some diseased specimens of carrots which had been growing at Chatteris, Cambridgeshire, where they had been obtained by Mr. Thomas of the School of Agriculture, Cambridge. Microscopic examination showed that they were attacked by Anguillulina dipsaci, and since this is the only record of the parasite on this host or, in fact, on any member of the natural order, Umbellifer it has been thought advisable to give an account of the chief symptoms of the disease shown by the plants.

In 1925, Morgan, in recording field observations on Heterodera schachtii in the Kirton district, pointed out that cysts were frequently as abundant in certain areas of infected fields where the yield was satisfactory, as in “bad patches” where the plants showed every manifestation of eelworm disease, and where the crop was a failure. In a further publication (1926) he again emphasized the lack of correlation between cyst content of the soil and the incidence of “potato-sickness.” One field on which detailed observations were carried out, although the worst case of eelworm infestation examined in the district, was found to give a satisfactory crop—average yield eight tons ware per acre—after only a four year rotation. In summing up these observations, Morgan says: “While it is not suggested that the eelworm had no influence on the yield in this instance, the success of the crop in spite of the pest lends support to the view that the problem is primarily one of obtaining more suitable conditions for plant growth by more judicious manuring and a system of rotation.”

Taylor (1928), in an attempt to infect starlings with the gapeworm, was able to infect six starlings out of fifteen which had been dosed, nine of which died before any observations could be made. The value of this experiment is, however, somewhat doubtful owing to the possibility of previous infection in the starlings experimented with, and the author concludes that in one bird, such was the case, owing to the size of the worms found.

During the latter half of 1930 and the beginning of the present year some miscellaneous experiments on Ascaris in pigs were carried out at the Institute of Agricultural Parasitology by Professor Leiper and myself. Although these experiments were of a preliminary nature it was thought that some of the observations made during their course might be of interest to other workers in this field and they are, therefore, placed on record.

Aphelenchus ritzemabosi is known as a serious parasite of greenhouse plants such as chrysanthemums and gloxinias but the number of records of its attacks on plants grown out of doors is increasing. Disease due to it has been observed in the open on chrysanthemums and dahlias in this country and in the present paper a new out-of-door host is added to the list of plants attacked by it.

In January, 1930, some free-living nematodes belonging to the genus Rhabditis were sent to Professor Leiper by Dr. Broughton-Alcock, who had found them in some fungal slime and débris accumulated in the drip from an ice-chest. Herein they are described as a new species of the genus, being named after the finder, and in view of their somewhat unusual habitat, some observations were made on the temperature reactions of the worms. The medium in which they were found proved unsuitable for the purpose of culturing, and at the suggestion of Professor Leiper a suspension in water of a mixture of powdered charcoal and faæ was used, which has proved very successful. Since January, 1930, pure cultures of the nematodes have been kept in this medium in the Department of Helminthology.

It has been, for some time, a recognised fact that intense eelworm infections are, in some instances, accompanied by only slight damage to the plants, while in other areas where the infection is much less intense, the plants show every symptom of “potato sickness” and the crop is a complete failure.

In August of the present year, specimens of young field-grown parsnips and carrots, showing heavily galled roots, were sent to this Institute by Mr. L. Ogilvie. The galls were found to result from eelworm infection, Heterodera radicicola being present in considerable numbers in the affected tissues.

Hymenolepis diminuta (Rudolphi, 1819), a normal inhabitant of thesmall intestine of the rat and other rodents and occasionally to be foundin man, has* received attention from several investigators desirous ofcontributing knowledge towards the life history of this cestode. Asa result of these researches it is now a well established fact that severalarthropods belonging to the Lepidoptera, Dermaptera, Coleoptera, Siphonaptera and Myriapoda can function as intermediate hosts althoughthis wide range of vectors is somewhat unusual.

While it is true that various lists of rat parasites have been published these, however, deal only with individual Classes of helminths. Notably amongst such publications are those by Hall (1916) dealing with the Class Nematoda, by Meggitt and Subramanian (1927) who treat of the Class Cestoda and by Dollfus (1925) who reviews the species of the Class Trematoda. It was suggested to me by the Imperial Bureau of Agricultural Parasitology that the collection of notes, records and information concerning the helminth parasites of common rats into one single work would be useful and the information contained in the three compilations mentioned above has been largely drawn on in forming the nucleus of this paper. Other publications, found helpful in providing additional information, are those by Balfour (1922) who deals with the parasites of wild rats in England, Baylis (1922), Cleland (1918), Fielding (1928), Johnston (1918), who summarises the knowledge concerning the parasitism of rodents in Australia, Meggitt (1924), Moll (1917), Shipley (1908), and Yorke and Maplestone (1926). For the more recent records, not included in any of the foregoing publications, the Vermes section of The Zoological Record and the “Répertoire des Genres nouveaux et des Espèces nouvelles,” appearing in each number of the Annales de Parasitologie humaine et comparée were consulted advantageously. The checking of many records, at least of the earlier ones, was accomplished by means of Stiles and Hassall's invaluable Index-Catalogues (1908, 1912, 1920).

Since the introduction of carbon tetrachloride for the treatment of the hookworm infestations of man it has been ascertained that in certain conditions fatal poisoning may follow oral administration of the drug. If carbon tetrachloride is given in cases of alcoholic cirrhosis of the liver, or if alcohol is taken immediately after the drug, severe gastro-intestinal symptoms are to be anticipated with death in two or three days. Davis (1924) showed that in dogs the toxicity of the drug was intimately associated with certain dietetic factors. He found that a high carbohydrate diet enabled the liver to withstand relatively large doses of the drug. High protein diets also protected the liver against injury (although less efficiently than carbohydrate) but an “all-fat” diet was invariably associated with extensive damage to the hepatic parenchyma. Lambert (1923) while carrying out hookworm treatment on a large scale in Fiji found that where a patient was heavily infested with Ascaris lumbricoides as well as with hookworm it was unwise to exhibit carbon tetrachloride without first getting rid of the ascarids.

The material here described was obtained from the large intestine of a Humboldt's Woolly Monkey (Lagothrix humboldtii) which died at the Zoological Gardens, London, about a month after it had been received there. In addition to the Enterobius infection there was a severe infection with Ascaris lumbricoides, involving both liver and small intestine. A single specimen of Necator was present, and along with the Enterobius were two immature female worms of doubtful identity, which are also described in this paper.

(1) The reactions of Dorylaimus under ordinary conditions of life are noted, especially its mode of progression and its burrowing habit.

(2) Some experiments were carried out with a view to finding out what physical and chemical stimuli are responsible for bringing about these reactions.

(3) The possibility of hydrotropism, thermotropism, geotropism, stereotropism, heliotropism and chemotropism are considered.

(4) The conclusion to be drawn from the data is, that taken on the whole, eelworms do not exhibit well marked tropic responses except in the case of stereotropism. It is obvious here, however, that they do everything in their power to put their body surface in contact with some solid object. This need explains why the worms are always found in the interstices of the zoogloeal film round the clinker. No other tropic response is needed to explain this habitat.

1. A preliminary account is given of certain serological investigations carried out on a rabbit fed with the embryonated eggs of Ascaris megalocephala.

2. By means of the complement-fixation test it has been shown that a definite immunity response occurs in the first five weeks of the infection.

During recent years the writer has had occasion to infest many rabbits with cercarial cysts of Fasciola hepatica. In all but three instances the infested rabbits have been killed within about ten weeks of the commencement of the experiment. These three rabbits remained infested over a long period and are the subjects of this note. They were kept under conditions which appeared to exclude all opportunity for further fluke infestation and no accidental infestation has been observed among the considerable number of similar rabbits used in other experiments during these years.

In June, 1930, the writer received from Mr. T. Meyer of Onderstepoort, some parasites collected from a red hartebeest at Gobabis in South West Africa. The examination of this material revealed the presence of rather long slender worms which could not be allocated to any of the known genera of the sub-family Trichostrongylinœ, Leiper, 1908. The genus Longistrongylus is proposed for the reception of this species which is named Longistrongylus meyeri gen. and sp. nov., in honour of the collector and donor.

In the experiments carried out by Nishigori (1925) and Saito (1925) on the life-history of Hepaticola hepatica it was shewn that this parasite does not reach maturity when a rabbit is artificially infected with embryonated eggs. It is true that the worms shewed some development, but after a time they disappeared leaving only nodules of connective tissue. In view of these results it may be of interest to record a case, observed by the writer where a rabbit carried a natural infection.

During the examination of an abnormal specimen of the Scottish Red Deer (Cervus elaphus) in the winter of 1930, my colleague, Mr. W. C. Miller, M.R.C.V.S., discovered several specimens of a bursate nematode lying on the connective tissue between the latissimus dorsi and the external intercostal muscles. Struck by the unusual habitat of such a worm, search was subsequently made in similar situations in other deer, and in two animals the same parasite was found.