During the course of work carried out in 1941 at the Plant Diseases Division, Auckland, N.Z., on a mixture of X strains in Red Dakota potatoes, it was found that among the twenty solanaceous species tested in host range studies, Cyphomandra betacea gave an anomalous reaction.

The determination of Hyalomma sp. is discussed. In the material examined from Palestine the genital aperture of the female, the cuticle in the proximity of the stigmata and the number of ‘tunnels’ in the anterior border of the scutum are characters which facilitate diagnosis.

1. Pure-line breeding of Calliphora erythrocephala is difficult owing to the fact that gravïd females will oviposit at a distance from decomposing meat and the newly hatched larvae will crawl long distances and pass through minute openings to reach the food.

2. A simple and convenient cage for breeding blow-flies is described.

3. To obtain eggs free from contamination meat is plunged in boiling water before being put in the cages; and the vessel in which it is placed is sup ported on a glass cylinder standing in a dish of water.

4. The larvae are fed on horse-meat placed upon sawdust in a large watch-glass resting upon sawdust in a bowl. The bowl rests upon a support surrounded by water.

5. Pupation occurs in the sawdust beneath the watch-glass and puparia are separated from the sawdust by sieving.

6. Pupae are kept in glass dishes with closely fitting covers to prevent parasitism by Hymenoptera.

7. At a temperature of 21° C. the complete life cycle takes about 1 month.

1. Compared with the mammalian intestine, uterus and blood serum, the corresponding organs and perienteric fluid of Ascaris lumbricoides were found to have a high phosphorus content. The muscle of the parasite, however, contained little more than half the phosphorus found in the mammalian muscle.

2. A. lumbricoides took up inorganic ortho-phosphate largely or exclusively through the alimentary tract. Small amounts were taken up by the cuticle and the lateral line system, but did not appear to pass on to other tissues.

3. Nippostrongylus muris in the intestine of the rat took up radioactive phosphorus which had been injected into the host intramuscularly. When the host was dosed per os the radioactivity appeared in the parasites at a lower concentration than in the host's small intestine.

4. Ascaridia galli failed to show any radio-activity when host birds were injected intravenously with inorganic orthophosphate containing P32. A sudden rise and fall in the radioactivity of the parasites were found when host birds were dosed per os.

5. It is suggested that nematode parasites have a high demand for phosphate which they take up largely per os. Ascaridia galli feeds rapidly, but with poor phosphate absorption, on host gut contents. Nippostrongylus muris feeds on host tissues. It is suggested that the different feeding habits of N. muris and Ascaridia galli may have some relation to the efficacy of anthelmintics against these parasites.

The authors are indebted to Dr M. Kamen and Dr E. Reinhard of Washington University, St Louis, for a gift of radioactive phosphorus. Thanks are also due to Mr E. Parrish and Mr L. Turk of the McMaster Laboratory for their capable assistance.

1. Qo2 values for Haemonchus contortus egs varied between − 9·7 and − 12·6 according to the degree of development of the embryos. The r.q. was in the region of 0·6.

2. Young infective larvae of Nippostrongylus muris had a high Qo2 (−18·4), which fell as the larvae aged. Third stage Haemonchus contortus larvae gave similar results. The respiration was not affected by exsheathment.

3. Adult parasites gave Qo2 values as follows: Ascaridia galli, − 2·5; Nematodirus spp., − 5·1; Nippostrongylus muris, − 6·8; Neoaplectana glaseri, − 12·6. When calculated on a surface area basis, Ascaridia galli had an oxygen uptake which was much higher than that of the other organisms.

4. Qco2 values were small. The r.q. of infective larvae, which contain fat as reserve material, was about 0·72. The other forms which contained much glycogen as well as fat had r.q. values between 0·6 and 0·7. A. galli was an exception in that an r.q. of about 0·95 was obtained.

5. Potassium cyanide inhibited respiration in all the forms examined.

The author is indebted to Dr R. W. Glaser for supplying a strain of Neoaplectana glaseri.

Three species of lung nematodes have been found in Felidae in Palestine: Aelurostrongylus abstrusus, Troglostrongylus brevior n.sp. and Anafilaroides rostratus n.g., n.sp. The life histories of all these species have been studied. Their larvae develop in terrestrial molluscs. Some new observations on the factors influencing the development of the larvae of Aelurostrongylus abstrusus are described. The whole developmental cycle of Troglostrongylus brevior has been experimentally reproduced. Initial stages of the development of the larva of Anafilaroides rostratus in molluscs have been observed. The taxonomic position of the genera Aelurostrongylus and Troglostrongylus is discussed and their protostrongyline character is demonstrated.

Four new species of myxosporidian parasites are described from marine fishes from Plymouth: Sinuolinea rebae n.sp., from the urinary bladder of Solea solea; Leptotheca vikrami n.sp., from the gall bladder of Zeus faber; Zschokkella russelli n.sp., from the gall bladder of Gaidropsarus tricirratus and Ciliata mustela; and Zschokkella sturionis n.sp., from the gall bladder of Acipenser sturio.

The various terms used in describing the spore of Myxosporidia are reviewed and revised.

A new classification is proposed of the order Myxosporidia.

I wish to thank the Director of the Marine Biological Association's Laboratory for all the facilities he has enabled me to enjoy during my stay at Plymouth, by dedicating a new species of Zschokkella to him. As a mark of gratitude, and with a deep sense of respect to His Highness the Maharaja of Narsinghgarh State, C.I., I take the liberty of dedicating to him the new species of Leptotheca I have discovered. But for his encouragement and help in the early stages of my career it would have been impossible for me to apply for the India State Scholarship which I now hold. I take this opportunity of expressing my thanks to Miss N. G. Sproston for her unfailing help and encouragement during the present studies and am very grateful to her for going through the manuscript critically.

1. The nomenclature and synonymy of the Leishmania of man and of the dog is reviewed.

2. Many of the older names have been discarded and medical writers now recognize only two, or at the most three, species of Leishmania of man and dogs.

3. These species are indistinguishable morphologically. Attempts to differentiate them by the techniques of bacteriology have given conflicting results and there is no general agreement that they can be so differentiated.

4. It has been suggested that separation of species of Leishmania is not justified under the present rules of systematics and that all forms of human and canine leishmaniasis must be regarded as the result of infection by a single species of parasite.

5. This suggestion is not entirely acceptable in view of contributions to the subject by medical workers who have studied the results of infection in the human subject intensively and continuously for half a century.

6. Evidence is produced that the different types of human leishmaniasis recognized clinically can be correlated with biological differences in the causal parasites.

7. In other organisms which have been intensively studied the existence of groups which differ from each other in biological characters only is widely recognized in modern systematics, but there is no general agreement about nomenclature for the definition of such groups.

8. Reasons, not inconsistent with modern studies in systematics, are given for the recognition of at least three groups in the Leishmania of man, corresponding with the L. donovani, L. tropica and L. brasiliensis of medical text-books. Definition of the taxonomic status of such groups will depend on the further progress of systematics.

Observations on the larvae of sheep trichostrongyles on hill pastures showed:

1. A reduction in larval populations occurred when the ‘moving-flock’ type management was used. The large proportion of eggs passed in faeces is deposited on a part of the pasture where little or no grazing occurs.

2. Local concentrations of larvae occurred on the grazed portions of a pasture when grazing was uneven. Thus, the apparent low rate of stocking on hill pastures does not give a true picture of the potential dangers of parasitic disease. Estimates of pasture contamination by Taylor's method of sampling were deceptively low.

3. The number of larvae on grass blades was lowest when the grass was wet with dew. Sampling of pastures between 12 noon and 5 p.m g.m.t. gave maximal and most constant estimates.

4. There was an increase in the number of larvae on a pasture during the warmer months of the year. While low temperatures prevent or delay hatching, the increase in population was not entirely due to the increased rate of development when temperature was high. The increase in numbers was partly due to an increase in the number of adult worms in the sheep hosts.

5. Removal of sheep for 3 weeks reduced the number of larvae on a pasture. This reduction was not apparent, however, until after the first 12 days. After 3 weeks the pasture population was reduced by 55 %, while after 4 weeks (i.e. 7 days after the return of the sheep) the reduction was 90%. Two weeks later there was a small increase in the larval population, but this was again reduced with the onset of colder conditions.

We need a fuller understanding of the feeding habits of fleas on rodents, both to help in the study of the epidemiology of plague and also in carrying out laboratory experiments on the same subject. In an earlier paper (Buxton, 1938) I described a ‘synthetic mouse hole’ in which I kept a rodent with a population of fleas (Xenopsylla cheopis) under controlled conditions of climate and feeding for periods of many days; with this I obtained some measure of the progeny which resulted under a variety of conditions. There was evidence that the mouse ate a number of the fleas, and I never controlled this variable, which was erratic and sometimes very large. We attempted to avoid the destruction of the fleas by feeding them on a baby mouse, which was changed at intervals, so that there was always one in the experimental vessel. In a postscript to the above paper it was shown that the baby mouse does not consume the fleas, almost all of which are alive when the experiment has lasted a week; in that period the adult mouse may eat about half or more of the fleas. Further experiments are in progress on the factors which determine the destruction of fleas by the mouse, and on the proportion of fleas which are actually found on the mouse under different conditions of temperature and so forth. In the present note, I shall confine myself to studying the baby mouse, as a host of X. cheopis. All the experiments here described were carried out between 1937 and 1939, though it has not till now proved possible to tabulate and consider the results. The execution of the work was in the hands of Mr S. Smith, whose help is acknowledged.

1. The rate of penetration of some representative drugs into Ascaris lumbricoides var. suis has been measured.

2. The series of 4-n-alkyl resorcinols shows a typical homologous series effect.

3. l-Nicotine penetrates relatively slowly.

4. Its rate of penetration is greatly influenced by the extent of dissociation of its methyl pyrrolidine basic group.

5. The rate of penetration of nicotine is greatly accelerated in the presence of some surface active substances.

6. Chloroform is the most rapidly penetrating substance studied, and its penetration is not significantly influenced by the presence of proteins, carbohydrates and fats and their products of digestion.

7. An analysis of the experimental results shows that the outermost layer of the cuticle of Ascaris is probably the main barrier to penetration. It behaves as if it were a thin; homogeneous layer of lipoid.

8. The significance of these results in the study of anthelmintics is assessed.

1. Attempts, made over a period of more than 6 months, to produce a strain of Plasmodium gallinaceum resistant to mepacrine failed.

2. A strain of P. gallinaceum resistant to daily doses of 0·08 mg./20 g. of pamaquin was obtained after approximately 8 months' treatment with the drug.

3. A strain of P. gallinaceum resistant to the maximum dose of paludrine which the chicks would tolerate (1·0 mg./20 g. twice daily) was obtained after 4½ months' treatment with gradually increasing doses of the drug.

4. The exo-erythrocytic parasites of P. gallinaceum formed in chicks infected with a paludrine-resistant strain are themselves resistant to the drug. It is not, however, considered probable that the development of resistance is due to the action of the drugs upon the exo-erythrocytic parasites, as the technique used was one which reduced their number to a minimum.

5. A strain of P. gallinaceum resistant to paludrine showed a normal sensitivity to mepacrine and pamaquin, but was resistant to 4430, the methyl homologue of paludrine.

6. Chicks carrying a latent infection of the normal strain of P. gallinaceum were immune to infection with the paludrine-resistant strain; and conversely chicks carrying a latent infection of the paludrine-resistant strain were immune to infection with the normal parasite.

7. A paludrine-resistant strain of P. gallinaceum retained its resistance to this drug after five cyclical passages through mosquitoes without intervening drug treatment.

The taxonomy of larval and nymphal stages of H. savignyi, H. detritum, H. marginatum, H. dromedarii and the nymph of H. aegyptium are described.

The material for the first four species was obtained from laboratory-bred specimens. The bionomics of these species was studied in the laboratory. Their behaviour under natural conditions still remains to be studied.

1. The morphology and life history of a gregarine Lankesteria culicis (Ross), as it lives in the gut of Aëdes (Finlaya) geniculatus (Olivier), are described. The earlier stages are intra-epithelial in the fore and anterior mid-gut of the larvae. After a period of growth the trophozoites are liberated into the gut lumen where they attach themselves to the epithelium by a well-developed epimerite which functions as a sucker. Cyst formation and further stages in sporogony take place in the malpighian tubules when the larvae develop into the pupae. In the adult mosquito only ripe sporocysts are found, packed in the malpighian tubules and scattered in the hind-gut. The spores escape through the alimentary canal.

2. The systematic position of Lankesteria is reviewed. In view of its true dicystid nature, combining both acephaline and cephaline features, it is suggested that its proper systematic position would be in the dicystid family Lecudinidae Kamm emend. Reichenow, 1929, which includes all forms intermediate in position between the monocystids and the true tricystids.

1. The distribution of Cimex hemipterus and C. lectularius in the Sudan is described. Leptocimex boueti has been found in two localities.

2. Reasons for the distribution of the two species of bed-bug are discussed, and it is considered likely that facilities for dispersal and atmospheric humidity may have been the most important factors.

A considerable loss of water in the flea larva, through its defaecation and excretion as the result of the absence of rectal glands, through a profuse evaporation from the surface cuticle on account of its being a soil inhabitant, and from its tracheal system owing to the absence of an efficient closing apparatus of the spiracles, is compensated by the absorption of water with the food and through the cuticle, and by the utilization of metabolic water.

It has been proved, by conducting experiments on the food composed of dried horse blood and yeast, with different degrees of moisture contents, and by controlling the quantity of the desiccated food and the duration of its exposure to a low effective humidity of 60% at 22° C., that the chief source of the gain of water in the larva of Xenopsylla cheopis is through the food.

The closing mechanism of the spiracles of the flea larva plays only a small part in the control of evaporation at medial temperatures but not at extreme ones.

There are intrinsic differences in the water requirements of the flea larvae of the two sexes, being slightly less in the male larva than in the female larva.

I am greatly obliged to Lt.-Col. Sir Sahib Singh Sokhey, Director, Haffkine Institute, Bombay, for affording me facilities for the pursuit of these investigations. Mr T. N. Raste has helped me in the calculation of the data statistically, for which I am grateful to him.

While investigating the nutrition of parasitic helminthes it became possible to estimate the amounts of several members of the vitamin B complex in the parasites. Information on this point was required in order to obtain some idea of the composition of a satisfactory in vitro diet.

1. The r.q. of whole Neoaplectana glaseri rose from 0·56 to 1·10 when glucose was added to the medium. The Qo2 was only slightly affected. Respiration of other nematode parasites was largely unaffected by exogenous glucose. Pyruvate had little or no effect.

2. Inorganic phosphate increased when Ascaris lumbricoides muscle brei was incubated. In the presence of fluoride, or when aqueous extracts were used, easily and difficultly hydrolysable phosphate was formed. Phosphatase activity was dominant even in aqueous extracts of A. lumbricoides intestinal tissues and fluoride inhibited Po formation only slightly. Ptot., and PresIdual fell markedly in whole A. lumbricoides which had been incubated anaerobically. Under aerobic conditions Po fell slightly, but the other components rose considerably. Phosphorylative activity of A. lumbricoides ovary was greater than in the muscle. Phosphorus compounds in perienteric fluid did not change during incubation.

3. The breakdown of glycogen and the formation of glucose in aqueous extracts of Ascaridia galli was inhibited by fluoride and phloridzin. Polysaccharide was synthesized in fluoride-poisoned preparations when glucose 1-phosphate was added. Polysaccharide formation in Ascaris lumbricoides fluoridepoisoned muscle preparations was demonstrated without the addition of Cori ester.

4. Fructose 1:6-diphosphate added to aqueous extracts of Ascaridia galli and Nematodirus spp. was rapidly metabolized at pH 6·5. At pH 7·2 the fructose content increased.

5. In aqueous extracts of Nematodirus or Ascaridia brei which had been autolysed for short periods, 55–60% of the glycogen utilized appeared as glucose. Only small amounts of lactate were formed. Aqueous extracts of Nematodirus and Ascaridia brei which had been autolysed for long periods formed glucose in excess of the glycogen disappearing. When perienteric fluid, which contained amylase, was removed from A. galli before autolysis, the amount of glucose formed was very much reduced. It is suggested that the excess glucose was formed from dextrins which were not estimated as glycogen and which were hydrolysed by perienteric fluid amylase during incubation.

Lactate decreased during the incubation of extracts prepared from brei which had been autolysed for long periods.

6. Bicarbonate decreased during the anaerobic incubation of aqueous extracts of Nematodirus spp. and Ascaridia galli which were buffered with CO2-bicarbonate. The decrease in bicarbonate was in excess of the CO2 expelled from the medium by acid formation.

7. The acid-soluble phosphorus compounds of the different tissues of Ascaris lumbricoides were examined. Compounds similar to a.t.p. were found in the intestine, ovary, muscle and possibly also in the perienteric fluid. The acid-unstable phosphorus compounds did not appear to be either creatine- or arginine-phosphate. Compounds similar to Embden ester were found in the ovary and muscle. The occurrence of the phosphate compounds found in the parasite is compared with figures given for other organisms.

8. It is concluded that carbohydrate fermentation as far as lactate in nematode parasites was similar to that found in yeast and mammalian muscle. Energy was transferred by means of high-energy phosphate bonds.

9. Phospholipids, which were found in considerable amounts in the tissues of A. lumbricoides, were estimated as lecithin, sphingomyelin and serine- and ethanolamine-containing phospholipids. The amounts of the phospholipids found in the parasite tissues are compared with figures given for other organisms.

The authors are deeply indebted to Prof. D. Keilin and Dr T. Mann of the Molteno Institute, Cambridge, for their advice and critical reading of the manuscript. Thanks are also due to Dr E. F. Gale and Dr E. Friedemann for advice on analytical procedures.