During some investigations in which, he has been engaged on the internal parasites of rats in the British Isles, Mr G. C. Dudgeon, of the Wellcome Bureau of Scientific Research, has kindly submitted to the writer examples of all the species of adult Cestodes found.

The foundation of an Institute for Research in Parasitology in Cambridge is an achievement worthy of being recorded in some detail since it affords a recognition of the value of a branch of biological science that cannot but gratify all who have gained an insight into the deep significance of the many problems which parasitology presents when viewed from the standpoint of pure science.

1. Rana clamitans of New York and R. pipiens from the middle part of the United States, were found to be infected by a Myxosporidian, apparently identical with Leptotheca ohlmacheri (Gurley) Labbé, found by Ohlmacher in the kidney of Bufo lentiginosus.

2. The Myxosporidian was found only in the space between Bowman's capsule and the glomerulus of the Malpighian body and in the uriniferous tubules of the kidneys of the host, no other organ being infected.

3. The mature spore contains two independent uninucleate sporoplasms which fuse into one prior to the germination in the posterior region of the stomach or duodenum of a new host.

4. The germination of the spore was observed in hanging drop preparations with the digestive fluid.

5. The youngest stage found in the lumen of the tubule of the kidney, was the uninucleate form.

6. The trophozoites multiply actively by a process of gemmation and probably also by a schizogony of the uninucleate forms.

7. The trophozoites are, as a rule, disporous and the spores develop independently of each other.

8. The vegetative nucleus persists throughout the entire trophic life of the individual.

9. The Myxosporidian does not exercise any fatal effect upon the host.

10. Infection takes place through the mouth. The liberated binucleate amoebulae probably penetrate through the wall of the small intestine, reach the coelom and are carried to the uriniferous tubules through the nephrostomes or blood vessels.

When fresh-water snails are examined microscopically, specimens are occasionally encountered that are infested with the cercariae of more than one species. Sometimes these cercariae are easily differentiated. A snail may harbour numerous eye-spotted amphistomes and a few distomes without eye-spots, or furcocercous forms may be associated with cercariae possessing undivided tails. In some collections of semi-stagnant water, however, the same individual snail may be found infested with at least two distinct schistosomes. In 1916, I found Physopsis africana (in an overflow pool along the course of the Umsindusi river at Pietermaritzburg) heavily infested with two distinct schistosomes, and it was not uncommon, as Dr E. E. Warren also observed, for the two forms to develop in the same host. One of these cercariae I named Cercaria secobii, the other was probably the cercaria of Schistosoma haematobium. Soparkar (1921 a and b) has moreover noted a double infection of Planorbis exustus near Bombay.

1. Heligtnosomum muris proved to be very favourable material for the study of nematode development, since it will develop perfectly normally in culture rats, infection is easily carried out and since sexual maturity is reached in 7–10 days after infection.

2. The post-embryonal development of H. muris is divided into five stages, two free and three parasitic, with three moults. There is only one moult during free life, the second and third stages being separated by change of habitat brought about by entrance into the host. Sexual maturity is attained soon after the completion of the third moult. The mature worm has two cuticular layers, the outer of which is separated by a space from the inner. This outer cuticula is probably the beginning of a fourth moult which is never completed.

3. Under favourable conditions the eggs hatch in about 20 to 24 hours after being passed with the faeces.

4. The first two stages of post-embryonal development, which are passed in free life, are separated by a relatively long moult during which the larva changes from the rhabditiform type to the filariform type. During this period there is a rapid division of the cells lining the intestine, which frees masses of these cells into the lumen and leaves the intestine of the filariform larva lined with flattened cells.

5. The infective stage is not enclosed in a sheath and tends to work its way out of the culture onto the glass or along the edges of the filter paper. At this stage it is impossible to distinguish the sexes.

6. Infection of the rat can be accomplished both by way of the mouth or through the skin although the latter method is by far the most effective. The larvae reach the lungs about 14 to 20 hours after penetration through the skin. They remain in the lungs until about 35 to 65 hours after infection. The majority of them reach the intestine 50 to 65 hours after infection, although in a few they were found as early as 45 hours.

7. In the lungs the larvae increase rapidly in size and moult just before they migrate to the intestine. Early in the development in the lungs the sexes can be distinguished by: (1) the migration toward the posterior end of the genital primordium of the female, (2) structural differences in the caudal region, and (3) differences in shape of the genital primordium.

8. After reaching the intestine the larvae grow rapidly and enter into the third moult from 96 to 108 hours after infection. In the fourth larval stage between the second and third moults growth and differentiation are most marked. It is during this stage that the differentiation of the organs of the reproductive system occurs.

9. Shortly after the completion of the third moult sexual maturity is reached and later the cuticula separates into two layers.

10. During the course of development the changes in size and shape and in the character of the cuticula were traced step by step and the differentiation of the digestive and excretory systems were followed as completely as the material would permit. However it was in following the details of the development of the reproductive organs that the investigation was most fully carried out.

11. In the male reproductive system the testes, vas deferens, seminal vesicle, cement gland and ejaculatory duct arise by differentiations of the genital primordium and are therefore called internal sex-organs, while the bursa and the spicules which are not developed from the genital primordium are known as the external sex-organs.

12. Toward the end of the third larval stage (first parasitic stage) the genital primordium of the male becomes separated into two parts by an extremely delicate strand of tissue. The anterior half of this genital primordium grows forward up to the oesophageal region and forms the testes, the narrow strand connecting the two parts develops into the vas deferens, and the posterior part grows backward to the posterior end, becomes tubular and forms the seminal vesicle, cement gland and ejaculatory duct.

13. The bursa is formed from the walls of the posterior end of the male which become very much inflated, and the spicules develop from secretions of a group of spindle-shaped cells which are early differentiated in the posterior region.

14. In the development of the female reproductive system the ovary, oviduct, seminal receptacle, uterus and the anterior part of the ovijector arise from the differentiation of the genital primordium and are therefore called internal sex-organs, while the vulva, vagina and posterior part of the ovijector arise from invagination and differentiation of subcuticular cells of the posterior end and are therefore called external reproductive organs.

15. After the genital primordium has migrated backward to a position on the ventral side just in front of the anus, it elongates very greatly and grows forward. The anterior part remains as a solid mass of cells and differentiates into the ovary. The rest of the primordium becomes tubular and differentiates into the oviduct, seminal receptacle, uterus and ovijector.

16. A group of cells just in front of the rectum and just over the posterior part of the genital primordium increases in number, invaginates, becomes differentiated into a tube which joins with the posterior part of the genital primordium. This tube differentiates into the vulva and vagina. Where it joins the posterior end of the internal reproductive organs there is an overlapping so that the posterior end of the ovijector has a double origin.

Complete specimens of this nematode are difficult to obtain, owing to the manner in which the worms bury themselves in the tissues of the urinogenital system of the Cetacea in which they are found. Mr A. G. Bennett, to whom the writer has previously been indebted on more than one occasion for Crassicauda material, has recently sent home further interesting specimens from South Georgia, accompanied by notes and a sketch which throw some light upon the burrowing habits of the worm. A special effort was made to obtain complete specimens by dissection.

1. Dacnusa areolaris Nees is a parasite of the fly Phytomyza angelicae Zett.

2. The egg is laid and development takes place within the body of the host.

3. A membrane of trophic cells is formed, within which the embryonic and first larval stages are passed.

4. The further growth and development of the parasite are delayed until after metamorphosis of the host, probably to ensure sufficient food in the later stages.

5. The length of the larval and pupal life of the parasite is intimately correlated with the puparial period of the host.

6. It is suggested that this is an adaptation to ensure that an adequate supply of host larvae shall be hatched by the time that the parasites are ready to oviposit.

7. Certain Chalcididae of the genera Eulophus and Chrysocharis are ectoparasites of Ph. angelicae, and a summary of observations on their life cycle is given.

In making the examination of a series of 400 rats, Heligmosomum brasiliense was found in 6 per cent. of those examined. The rats were all of the one species, Epimys norvegicus, and were chiefly from London and suburbs; the exceptions being one from Berkshire, one from Hampshire and two from Hertfordshire.

1. Collections of flukes made in several centres in China include 25 species of cercariae.

2. Fourteen of these species are described as new.

3. Details of the excretory system are presented for six of the species described. In two of these instances (echinostome larvae and furcocercarjae) differentiation within thenatural group is demonstrated, while in two other larvae, C. styloidea and C. diophthalmica, proof of relationship and correlation with adult groups is established.

4. C. abbrevicauda shows striking resemblances to the larva described as the cercaria of Paragonimus westermanni and may possibly be regarded as identical with the larval stage of that worm. Moreover, the host genus is the same.

5. The stylet organ is shown to be non-specific and the group of the “xiphidio-cercariae” to be a composite of several natural families.

6. No organs of the cercaria save the cephalic glands and flame-cells have thus far proved satisfactory for differential diagnosis of the larva.

7. Further study along these lines will make it possible to demonstrate natural groups where only artificial groups now exist.

Cysticercus Fasciolaris, the larval stage of the common tapeworm Taenia taeniaeformis (T. crassicolis), was recently found in great numbers in the liver of a brown rat. The rat measured 18 cm. in length and weighed about 275 g.; it was vigorous and apparently healthy when caught, but when killed and examined, its liver was found to be heavily infested with the cysticerci.

Léon Dufour was born 11 April, 1780, at Saint Sever (Landes) and died there 18 April, 1865. He was a medical man and a naturalist. He took his M.D. at Montpellier ir 1806. From 1806 to 1814 he served in the army, then turned his attention to entomology and botany, but in 1823 he took part in the Spanish Campaign as an army doctor. He distinguished himself especially through his work on the anatomy and physiology of arthropods and upon the habits and metamorphosis of insects, but he also wrote on botany, agriculture and meteorology. He was elected to the Academic des Sciences and was the first Frenchman upon whom that body conferred the Cuvier Prize (1861). During 1811–1864 he published 232 papers on entomology, the relation of insects to plant diseases, parasites of Insects, parasitism, Protozoa and Helminths.

Lambs contract Moniezia infection either at or very soon after birth, since they have been observed to harbour adult worms at 2–3 months old and in one case, to pass proglottids at 4–6 weeks.

The intermediate host, if such exists, must be frequent on the pasture in early spring, otherwise lambs would not be found to harbour adult tapeworms so regularly or in such numbers when slaughtered in early summer. In the small intestine of a lamb from 3–4 months old slaughtered at Aberystwyth, there occurred 75 individuals.

The fact that lambs regularly harbour adult tapeworms before they are weaned suggests the possibility of their contracting the infection from the mother-ewes. No direct evidence in this direction has been obtained, however, and an attempt to produce a larval stage in the udder region of a ewe by feeding to it the eggs of a tapeworm proved abortive.

Hitherto, all attempts to produce the adult tapeworms directly by feeding the eggs to sheep have failed; there is, however, the remote possibility that the eggs require to undergo some kind of maturation process outside the body of the sheep before they will develop. The fact that several species of Moniezia occur in the domestic sheep would seem to require an intermediate stage, which would occur in a corresponding number of intermediate-host species.

The disease seems prevalent in flocks which are singularly free from ectoparasites.

The invertebrates which seem most likely to harbour an intermediate stage are coprophagous insects, etc. (beetles, flies, mites). Attempts to infect species of Aphodius have nevertheless proved fruitless.

Moisture favours the survival of the eggs of Moniezia: eggs kept in water for a period of several months seemed to remain perfectly viable. Nevertheless tapeworm is common among flocks on pastures about Rome which are characteristically dry.

A comprehensive series of experiments under conditions of the most complete control would almost certainly clear up the life-history; on economic grounds alone the problem is urgent.

The overwhelming majority of a quantity of worms collected from slaughter-houses in Aberystwyth, Aberdeen, Beauly (Inverness-shire) and Newcastle-on-Tyne proved to be of the species M. expansa. The only other species found were M. trigonophora and M. alba. The identification was based on anatomical characters and not on externals, which are useless.

The writer intends directing his attention to coprophagous mites as carriers, viz. Gamasus coleoptratorum, G. fimetorum, Macrocheles glaber.

The approach to the study of the ectoparasitic flies of the pupiparous family Hippoboscidae has heretofore been almost entirely by way of the conventional methods of the Dipterists. In other words, descriptions have been based almost exclusively upon pinned specimens. Consequently these descriptions have, for the most part, considered only the conventional subjects of colour, wing venation, size, shape, form of the claws and a few of the more obvious chaetotactic characters. A few descriptions have been based upon alcoholic specimens and these descriptions are decidedly better than those based upon pinned specimens, although they still leave something to be desired.

1. Attempts to secure a micro-organism which could induce abortion or sterility in wild rats and which might be used in an anti-rat campaign, more especially when plague threatens a community, have not been successful.

2. An account, however, is given of certain micro-organisms producing pathological conditions in the genito-urinary tract of wild rats.

3. A routine determination of rat parasites including ecto-parasites, helminths, intestinal protozoa and haematozoa has been undertaken.

4. It has led to the discovery of a new species of Hymenolepis and has shown that Heligmosomum braziliense is present in rats in England. It has also demonstrated the occurrence of haemogregarines in the leucocytes of black rats in this country.

5. Work has been done on the incidence of Leptospira icterohaemorrhagiae in Rattus norvegicus and Rattus rattus in England and on the mechanism of its transmission.

6. It has been shown that apparently the guinea pig may act as a carrier of the Leptospira without exhibiting any marked symptoms of the disease which the latter produces. There is also some evidence to prove that infection may take place through the alimentary tract.

7. The Leptospira was successfully and easily cultivated in Wenyon's modification of the Noguchi method but in large measure lost its virulence as the result of repeated subcultures. Even after a year, however, it was still capable of producing characteristic symptoms in the guinea pig.

8. General pathological conditions occurring in wild rats have been recorded.

9. A few observations have been made on the seasonal incidence of pregnancy in wild rats.

The parasite herein described was found in the intestinal contents of Blatta americana at Calcutta. The species seems to be comparatively rare and was observed twice only. It may be named B. blattarum sp. nov.

1. The biology, as studied under laboratory conditions, of O. savignyi is very similar to that of O. moubata.

2. Females may oviposit over 400 eggs, of which at least 60 per cent, may be fertile; parthenogenesis does not occur.

3. An increase in temperature of 8° C. (from 22° C.) decreases the longevity of the female from 775 to 358 days, i.e. by 45 per cent.; an increase of 7° C. (from 30° C.) reduces the period required for the production of third stage nymphs by 26 per cent. At 30° C., the mean minimum periods required for metamorphosis are 60 days for males and 73 days for females (cf. O. moubata, 36 days for males and 45 days for females). Reproduction was inhibited at 37° C.

4. Moisture is an unfavourable factor, decreasing the vitality of the individual at each stage of growth.

5. Changes in external anatomy undergone during development are similar to those already described for O. moubata.

Dujardin (1845) was the first to give a satisfactory account of the small Strongylid worms inhabiting the intestinal tract of field-mice and voles. His descriptions of the various species were careful and for the most part accurate, they were, unfortunately, not accompanied by figures, and incomplete in that the characters of the bursal rays of the males were not given, an omission which has led to considerable confusion, since the modern classification of the Trichostrongylidae is based largely on the structure of the male bursa.

This gregarine was found inhabiting the alimentary canal, and especially the midgut, of both larvae and imagines of Anobium paniceum. All the larvae examined, and most of the adult beetles, were found to be very heavily infected, and in some of the larvae almost every epithelial cell harboured one or more of the cephalont stages of the parasite (Fig. 1). The lumen of the midgut of these larvae was densely packed with the freely moving sporonts, and a number of newly formed cysts were visible in the hindgut. In the imago only the cephalont stages were observed, and no sporonts or cysts have been found.

The growing importance of the silver black fox industry in Canada, and latterly in other countries, has been so marked, that scientific workers have turned their attention to a study of the maladies affecting this species of fox.

A tumour among the gill filaments of Trigla gurnardus bears a female Medesicaste with the head and neck buried in its apex, and a male Medesicaste completely embedded in its base. The two sexes of the parasite are connected by a conjugation tube, external to the tumour, down which tube the spermatophores presumably pass. The appendages of the copepod are described.