1. The inhibitory effect of Ascaris extract on pepsin and trypsin is confirmed. This inhibition is shown not to occur with papain.

2. The inhibitory effect is shown to be brought about by a combination of the anti-enzyme with the enzyme and not by any of the other possible causes.

3. The extract is shown to have a proteolytic as well as an inhibitory action and these two properties are shown to be due to one and the same substance.

4. The term “ascarase” is suggested for this substance.

5. The ascarase is shown to be a readily diffusible substance of the order of a primary albumose, is precipitated by ammonium sulphate and 70% alcohol, is only slowly destroyed in acid but rapidly in alkali and is not digested by trypsin. It combines with the greatest quantities of substrate at pH 5–7.

6. Ascarase is found in the various tissues of the worm in the following order: ovary, oesophagus, gut, body fluid, ovojector, lateral line, uterus and cuticle. A similar order was found for the male.

7. The results found by de Wael (1933) for T. saginata do not apply to Ascaris.

8. The effect of the ascarase on the host and its function in the worm are discussed.

Protection against infection with Trichinella spiralis is conferred upon mice by the passive transfer to them of a specific immune serum from rabbits. A smaller percentage of mice treated with the immune serum die, and fewer larvae invade the muscles of the treated mice than among control animals. The action of the antibody of the immune serum appears to be directed specifically against the ingested larvae which are maturing to adult worms in the intestine of the infected animals. The results obtained thus far indicate that an immune serum would have little therapeutic value in the later stages of the disease.

The genus Pseudaspidodera was founded by Baylis & Daubney (1922). Recently I had an opportunity of examining a collection of worms of this genus from the gut of two Indian peafowls, Pavo cristatus. I am grateful to Mr K. K. Banerjee of the Bengal Veterinary College, Calcutta, for kindly placing the material at my disposal. Three species of the genus Pseudaspidodera have so far been described, viz. P. pavonis Baylis & Daubney (1922) from Pavo cristatus and Pavo muticus, and later from Argusianus argus; P. voluptuosa Chandler (1926) from Argusianus argus and Rollulus roulroul and P. spinosa Maplestone (1932) from Argusianus argus. The parasites under consideration cannot be assigned to any of the species referred to above. The separation of the cephalic cordons in P. pavonis, the presence of spines along the cephalic cordons in P. spinosa, and the longer left spicule in P. voluptuosa are sufficient to distinguish these worms from my specimens. I take this opportunity of recording my sincere thanks to Dr Baini Prashad and Mr M. N. Datta of the Zoological Survey of India for giving me facilities for examining the type specimens of P. pavonis and P. voluptuosa. I am indebted also to Prof. P. A. Maplestone of the School of Tropical Medicine and Hygiene, Calcutta, for kindly lending me the co-types of P. spinosa. The species has been named after one of my colleagues, Mr Jnanendra Lal Bhaduri, M.Sc., who has helped me with many helpful suggestions.

About a year ago when examining the intestinal contents of various fresh-water fishes of Bengal, I obtained a new acanthocephalan parasite, Acanthosentis dattai, from the small intestine of Barbus ticto and B. stigma. In a single host as many as twenty were obtained, but the average number of parasites taken from other hosts was four to ten. Some of these were found lying in a sluggish state in the lumen of the intestine. About the months of July and August some were found in copula.

References to dipterous parasites of Diptera are rare in the literature. Bombyliids of the genera Villa and Thyridanthrax have been reared from the puparia of Glossina; Hemipenthes morio L., from the tachinid Parasetigena segregata Rond., and the sarcophagid Sarcophaga affinis Fall.; Argyramoeba varia F. from the tachinid Sturmia inconspicua Mg. The phorid Hypocera incrassata Mg. was found by H. M. Morris in dead and unhealthy larvae of Bibio marci L. Only one larva of Hypocera was obtained from each specimen of Bibio, and the account given by Morris suggests that this species is a true parasite. The evidence is, however, not absolutely conclusive and further study of this interesting species is desirable. The same thing must be said of E. E. Edwards' record of Aphiochaeta brevicostalis Wood, as a parasite of Tipula sp.

1. Histomonas meleagridis was isolated in culture from the liver lesions of a hen suffering from “blackhead” (enterohepatitis). It has been cultivated at 36·5–37°C. for over a year.

2. Chicks, which had been reared free from protozoa, were inoculated per os or per anum, with cultures of the above strain of H. meleagridis. Eleven out of twelve birds became infected. Caecal lesions only were produced. This strain, although isolated from the liver lesions of a hen suffering from acute blackhead, showed no abnormal virulence in chicks.

3. Individuals of this strain of H. meleagridis showed amoeboid movement but were also flagellate. Normally the protozoon was uninucleate, but binucleate forms were common, and tri- and quadrinucleate forms occurred more rarely. One flagellum arose from each nucleus.

4. During division the flagellum disappears. The method of nuclear division was similar to that of Trichomonas.

5. A resistant phase was never seen in the cultures.

1. The life-history of Entamoeba coli (from a marmoset, several macaques, and Man), as observable in cultures, is here described and illustrated. It is found to be similar, in general outline, to that of E. histolytica, but to differ considerably in its excystation and metacystic stages.

2. At excystation, the entire contents of the cyst usually escapes, as a single multinucleate amoeba, through a large opening in the cyst wall, which is composed of two layers.

3. Normal ripe cysts frequently lose 1 to 4 of their 8 original nuclei before hatching, thus becoming “infranucleate” (i.e. containing only 4 to 7 nuclei instead of the “typical” 8).

4. During the metacystic stages no nuclear divisions occur. The hatched amoeba eventually produces, by a series of binary cytoplasmic fissions with random nuclear distribution, as many uninucleate amoebulae as it originally contained nuclei.

5. An originally 8-nucleate cyst may therefore produce 8 amoebulae finally –never more: but owing to the frequent development of infranucleate forms, it often produces only 7, 6, 5, or 4.

6. Development is complicated by occasional division into two within the cyst before hatching, or at the moment of hatching—such divisions being seen in both “typical” and “infranucleate” cysts; and also by the occurrence of supernucleate cysts (containing more than 8 nuclei), which are often viable but usually develop in an infranucleate condition. Consequently, amoebae containing any number of nuclei from 1 to 8—or even more—may hatch from the cysts of this species (unlike those of any other hitherto described).

7. The uninucleate amoebulae resulting from the metacystic divisions are young trophic amoebae—not gametes—and no sexual stages occur in the life-cycle. Division of the trophic amoebae is briefly described and figured.

8. The life-cycle of E. coli is finally compared with that of E. histolytica and related species: the relevant observations of other workers are briefly analysed: and the taxonomic implications are noted.

A memorandum is added on the genus Entamoeba, in an attempt to clarify the nomenclatural and taxonomic confusion created by Opinion 99 promulgated by the International Commission on Zoological Nomenclature. This leads to the conclusion that the Opinion itself is a dead letter, though the genus Entamoeba still lives and should therefore be retained, for the time being, with E. coli Casagrandi & Barbagallo, 1895, as its type.

To students of the literature dealing with amoebic dysentery the name of O. Uplavici is probably not unfamiliar: but few authors are aware, apparently, of his singular story, so the following lines recording his life and death may therefore be acceptable to readers of Parasitology.

The morphology of a micro-organism, Cytœcetes microti, new genus, new species, which invades the granulocytes and occasionally the lymphocytes, is described. It occurs naturally in the vole, Microtus pennsylvanicus, is transmissible to white-footed mice, Peromyscus leucopus and Peromyscus eremicus, the common tame mouse, the white rat, but inoculations of guinea-pigs. domestic rabbits, a kitten and young chickens have resulted negatively. The only pathological effect attributable thus far to this organism is an increase in the number of granulocytes found in certain organs such as the spleen and adrenals, and degenerative changes in the individual cell invaded. Splenectomy performed soon after the microscopic disappearance of Cytœcetes from the circulating blood may result in its reappearance, when it may occur in a considerable proportion of the granulocytes, but nevertheless in smaller numbers than at the height of early infection. Overwhelming infections have in no instance followed splenectomy. The probable relationship of the organism to Ægyptianella pullorum (Carpano, 1928) is pointed out, but grounds for placing it in a separate genus are presented.

The four new species of Macropostrongylus Yorke & Maplestone, 1926, and the one new species of Pharyngostrongylus Yorke & Maplestone, 1926, which are described in this paper formed part of a collection of nematodes obtained by the Australian Institute of Tropical Medicine, and forwarded by Dr G. M. Heydon to the British Museum (Natural History). Co-type specimens will be deposited in both institutions.

Echinorhynchus gadi (Zoega) Müller has been found parasitic in various species of Pacific salmon. The amphipod Cyphocaris challengeri Stebbing serves as an intermediary host for this parasite in the region in which the investigations were carried out.

Echinorhynchus lageniformis sp.nov. and Corynosoma strumosum (Rudolphi) both parasitic in the Starry flounder (Platichthys stellatus (Pallas)) and the Two-lined flounder (Lepidopsetta bilineata (Ayres)) are recorded with data on their occurrence.