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. 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.

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.

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.

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.

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.

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.

Parasitology, owing to its economic importance, has received very great attention during the last 50 years and several good text-books have been devoted to this subject. In almost all recently published books, however, stress has been laid chiefly upon the economic side of the problem: medical, veterinary, agricultural, etc., but the scope of Parasitology is by no means restricted to the problems economically connected with man. We know now that there is hardly any group in the animal or vegetable kingdom which does not harbour parasites. The latter themselves do not escape this rule and are often parasitised in their turn. Moreover, the interrelations between living organisms are not restricted to parasitism only; there are, in fact, all shades of transition between parasitism on the one hand, and commensalism and symbiosis on the other. These interrelations have never been adequately dealt with in text-books of biology or parasitology and all the information concerning them is scattered in a great number of papers dealing with various biological or parasitological problems. This gap has been recently filled by a small volume issued by Prof. M. Caullery [of the “Laboratoire d'Evolution des Êtres Organisés de la Sorbonne, Paris” under the title Le Parasitisme et la Symbiose in which the author has incorporated a series of lectures delivered by him on this subject during the academic year 1919–1920. The book deals with the most interesting cases of commensalism, parasitism, and symbiosis and with various important cases of transition between these three great ethological groups.