1. An outline of the life history of Cephus pygmaeus Linnaeus is given.

2. The parasites of Cephus are listed and are discussed briefly in relation to the particular parasite Collyria calcitrator Gravenhorst.

3. It is shown that if the host larvae collected from wheat-stubble in autumn are used for the investigation of the extent of parasitism by Collyria, allowance must be made for the fact that the parasite Pleurotropis benefica Gahan is intrinsically inferior to Collyria, and that its cocoons must represent hosts left unparasitized by Collyria.

4. In summer the adults of Collyria emerge, on the whole, earlier than those of the host Cephus. This suggests that at the beginning of the season of oviposition there will be a scarcity of hosts in comparison with the numbers of parasites wishing to oviposit. The relative activity of host and parasite during the egg-laying period is worked out on hypotheses of the average length of life of the individuals, and is shown diagrammatically.

5. The Cephus larvae travel down the stem and hibernate at the base. When the wheat is cut, a proportion of the larvae and their parasites are removed with the straw. The way in which this may prevent the stubble material from giving a true indication of the degree of parasitism in the population as a whole is discussed.

6. On the basis that 3910 hosts receive 3600 parasites, various hypothetical distributions are worked out arithmetically in order to find which type of discrimination between healthy and parasitized hosts gives an arrangement of parasites most in agreement with what has been found for Collyria in Cephus. The most satisfactory result is that obtained when it is assumed that the probability of an already parasitized host being re-attacked varies with the proportion of parasitized hosts. It is also shown that a shortage of hosts at a time of parasite activity may cause a high degree of superparasitism, thus giving a false impression of the parasite's power of discrimination.

7. Suggestions for further field work are given.

Among the new facts discovered in the course of the writer's investigation on the function of the polar filament of the spore of Nosema bombycis (Ohshima, 1927), the following two are considered the most important:

(1) As soon as its filament extrusion is accomplished in the midgut of a silkworm, the spore discharges a viscous fluid through the tube of the filament. This fluid remains hanging in a spherical shape at the extremity of the filament.

(2) Both the polar filament and the viscous fluid are speedily digested by the digestive ferment of the silkworm in a few seconds.

An account is given of the spontaneous occurrence in the Anglo-Egyptian Sudan of strains of the camel trypanosome, Trypanosoma evansi, devoid of kinetonuclei.

These cases, of which four are recorded, were observed in widely separated localities within the enzootic area of camel trypanosomiasis.

A critical review is given of the question of “akinetonucleate” trypanosomes in general—in strains produced experimentally and in those occurring spontaneously—with special reference to their mode of origin and their significance in the production of new races.

The prevalence of “akinetonucleate” forms in normal strains of trypanosomes has been estimated in the case of a number of species and races hitherto not examined from this point of view, all the existing data being brought together in tabular form.

While the factors causing the appearance of “akinetonucleate” individuals and strains under natural conditions could not be ascertained, irregular division of the trypanosomes is held to be mainly responsible for the elimination of the kinetonucleus and for the persistence of the aberrant condition.

The present report is confined to the species found in Chinese amphibians by Faust in his field studies during the period from 1920 to 1925. Two new species of the genus Acanthocephalus are described in this paper and notes on their geographical distribution and host relationships are included along with observations on the occurrence of undetermined species of encysted larval Acanthocephala in amphibian hosts.

1. In Entamoeba aulastomi excystation does not occur in vitro until the glycogen and chromatoids have been absorbed.

2. The product of excystation is a quadrinucleate amoeba.

3. The amoeba escapes through a minute pore in the cyst wall.

4. No evidence of sexual phenomena has been obtained during the metacystic cycle.

5. The excysted quadrinucleate amoeba undergoes a series of nuclear and cytoplasmic divisions. These divisions do not necessarily synchronize or alternate with one another, but by them 8 uninucleate amoebulae containing daughter nuclei are ultimately produced from every cyst. Amoebae containing 6, 7 or 8 nuclei may appear in the course of the metacystic development.

A brief summary of previous work done on the life history and the biology of fleas is given. The duration of various well-defined periods during the course of metamorphosis of the flea at temperature 23° C. and 90 per cent relative humidity is recorded.

It is experimentally proved that blood, although the most important part of the nutritional requirements of the flea larvae, is by itself not sufficient for their normal and successful development. The flea larvae require an additional food which in nature is supplied by the organic refuse present in the bed of the host of the adult fleas.

Experiments were carried out to determine the nutritional value of different constituents of the blood and it was found that the fibrin has no nutritive value to the flea larvae, while the serum and red corpuscles have equal nutritive value. Lagging larvae are the result of some deficiency in the food. The serum possesses all the essential proteins for the normal development of flea larvae but lack of the required amount of iron in it increases the percentage of mortality and delays the development. On the other hand the red corpuscles or haemoglobin, though rich in proteins containing iron but on account of the poverty of some other proteins necessary for the normal development prolong the development and increase the percentage of mortality. It was further experimentally proved that flea larvae require blood for their development in order to obtain the necessary supply of iron for their normal growth. The denatured proteins of the blood and its constituents have no nutritive value for the flea larvae.

1. Investigations into some of the problems associated with African East Coast fever and its vectors have been undertaken: and although these are, as yet, incomplete we consider them of sufficient interest to warrant their publication at this stage.

2. The present position regarding the distribution of certain tick species in relation to East Coast fever in Kenya is briefly reviewed; and outbreaks of what may be peculiar forms of the disease in sporadic areas are mentioned.

3. It is thought that the passage of Theileria parva through different species of ticks might throw light on some sporadic outbreaks of the disease and on the peculiar character of some of the cases encountered.

4. Transmission by nymphae and adults of Rhipicephalus appendiculatus, by adults of R. evertsi and R. simus is confirmed. Experiments with R. sanguineus, R. pulchellus and Amblyomma variegatum were negative.

5. Exposure of infective nymphae of Rhipicephalus appendiculatus to different degrees and conditions of temperature prove that the ticks remain infective after being subjected to 4–6° C., and 8–10° C. for 1, 2 and 3 weeks. Exposure to different alternating temperatures for similar periods had no effect on the virulence of the parasite. The ticks exposed to warm temperatures (35–38° C,) did not survive to the same extent as those exposed to cold temperatures. Ticks that survived for 1 week transmitted the disease.

6. Animals that ultimately recover from artificial infection may show a mild thermal reaction during the short course of the disease without showing typical clinical symptoms. In such cases diagnosis is frequently difficult, and Koch's bodies may be rare.

7. The association of Hyalomma spp. with many different diseases is briefly dealt with; and it is shown that Hyalomma impressum near planum P. Sch. is capable of transmitting East Coast fever in the nymphal and the adult stages after the larvae and nymphae respectively have fed on an infected animal. The parasite does not pass through the egg. H. impressum near planum is common in most parts of Kenya Colony.

The object of this paper is the description of a dipterous larva based on the study of six specimens of larvae obtained by Mr R. A. Phillips from living specimens of the snail Vertigo genesii Gredler which he had caught at Cloanascragh Bog, near Taum, Co. Galway. Three larvae were received in October 1933 through Prof. Boycott, and three in September 1936 directly from Mr Phillips. In a letter accompanying the specimens Prof. Boycott makes the following remark:

“Considering that the whole snail shell is only about 2 mm. × 1 mm. the larvae seem very big.” In fact some of the shells are distinctly smaller than the adult larvae, which when mounted are 2·0–5·0 mm. long, and 0·3–1·5 mm. in diameter.

The coccidian dealt with in this paper is a parasite of the blood, fat bodies and connective tissue of Tribolium ferrugineum. W. A. Riley and L. Krogh were the first and perhaps the only ones who noticed stages of this parasite, when studying the histology of the larvae of this beetle. They found the pupae and adults uninfected, but in the course of the present work some of them were heavily infected, though only a small number could be examined.

I wish to record some unidentified parasites, from the abdominal cavity of a Queen Bumble-bee (Bombus terrestris).

A case of a heavy infestation of Cysticercus tenuicollis, terminating fatally in a deer, was recently afforded by one of the experimental animals of the Dominion Entomological Branch (Livestock Insect Investigation Laboratory) at Kamloops, B.C.

An account is given of a virus which is present in the roots of a number of different plants. Plants which have been shown, so far, to contain the infective principle in the roots are several members of the Solanaceae, tomatoes, tobacco, etc.; of the Primulaceae, Polyanthus sp. and Primula obconica; of the Geraniaceae, zonal Pelargonium; and of the Compositae, the aster. Such plants show no indication of infection with the exception of Nicotiana tabacum and N. glutinosa, which may develop natural disease symptoms. These symptoms are usually confined to the two lowermost leaves and develop most frequently under conditions of low temperature and low light intensity. The virus never becomes completely systemic in any host plant and is generally restricted to the inoculated leaves. Experiments are described which show the virus to be present in the roots of tobacco plants which had given a negative virus reaction a few weeks earlier. The virus is found in the roots of tobacco plants arising from seed which has been heated to a temperature of 75° C., the thermal death-point of the virus in expressed sap being 72° C. All attempts to demonstrate the presence of the virus in the seed have proved negative.

Although no systematic study has been made, the range of plants susceptible to local infection in the leaves, by artificial inoculation, seems wide. Tests have shown that about 25 species of plants belonging to 10 families respond to inoculation with the virus.

Three possible explanations of the origin and spread of the infection are discussed.

In a previous paper (1931) the writer described the presence of a spicule in the male of Capillaria [Hepaticola] hepatica, and gave reasons for believing that the apparent presence or absence of a spicule in the males of forms closely related to it is not a reliable taxonomic character. It was suggested that the genus Eucoleus Dujardin, which, like Hepaticola Hall, was based mainly on the supposed absence of a spicule, should likewise be suppressed as a synonym of Capillaria. Teixeira de Freitas & Lent (1935, 1936), in accepting this view, have drawn attention to an observation recorded by Creplin (1849), which had been generally overlooked, to the effect that a spicule is present in the genotype of Eucoleus (Trichosomum aërophilum Crepl., in Ersch & Gruber, 1839). Up to the present Creplin's observation has not, so far as the writer is aware, been confirmed. Some specimens of Capillaria aërophila from the lungs of silver foxes were recently received from Mr C. V. Watkins, M.R.C.V.S., who had noticed in a living male specimen what appeared to be a spicule projecting from the everted spicule-sheath, and enclosed a sketch of it in his letter. On examining the preserved material, the writer was able to confirm this interesting observation. In the specimen referred to by Mr Watkins, and in another individual, a very delicate structure, apparently a spicule, was seen projecting for a short distance beyond the end of the partly everted sheath.

A method is described by which active cutaneous myiasis of sheep by Lucilia sericata larvae can be produced with certainty and precision at any season of the year. The method is such that it can readily be employed in field experiments.

The results are described of further studies on a virus found in the roots of certain normal-looking plants. It is shown that the virus is a contamination arriving from outside sources. The virus has been detected in the sludge at the bottom of the water tanks, and the experimental evidence shows that it is water-borne to the soil whence it reaches the roots of the plants. Experiments to test the possibility that the virus is also air-borne have so far proved negative.

The virus is exceedingly resistant, it can be completely desiccated and remains infective in the dry state for many weeks. It is also unaffected by alcohol and is still infective after being stored in absolute alcohol for 6 months.

The virus is thought to be a transitional stage between a pathogen and a non-pathogen.

From the foregoing brief descriptions it is clear that the larva of Trichomyia urbica stands apart from other psychodid larvae not only in its mode of life, as a wood-borer, but also in its morphology. The regularly cylindrical body, devoid of dorsal plaques and long setae and the densely chitinized head give it a very different appearance from that of other psychodid larvae.

The small and heavily chitinized antennae are very different from those found in larvae of Phlebotomus, in which they are 3-segmented; Psychodes, in which they are delicate and dome-like; Sycorax, in which they are long and 4-segmented (Feuerborn, 1933); and Maruina, in which they are formed of small rods (Feuerborn, 1933).

The massive toothed mandibles, devoid of sensory processes, differ greatly from those of other genera of psychodids except Phlebotomus. Maruina, Sycorax (see Feuerborn, 1933), and Psychodes all have mandibles with large leaf-like processes and many long plumose or pectinate setae and sensory hairs or processes.

The maxillae, in all the three genera examined above, are delicate plates with ill-defined areas representing the maxillary palps, and with many delicate teeth, long setae and sensory processes arising from the body of the maxilla.

The lower lip in Trichomyia is very simple and the mentum is hardly distinguishable. In this respect it resembles Psychodes where the mentum is a simple transverse plate, and Maruina (see Feuerborn, 1933) in which it is similar except that the anterior border of the plate is fringed with long setae. In Phlebotomus the mentum is a densely chitinized plate with strong teeth on its anterior margin.

The anterior spiracles appear to be much alike in all the genera in which they are present; but in the position of the posterior spiracles Trichomyia, in which they are placed far back on the dorso-lateral region of the last segment, differs from all other genera examined except Phlebotomus, in which they occupy a similar position.

Therefore, as regards the shape of the body, nature of the cuticle, absence of long setae and of dorsal plaques, and the structure of the antennae and labrum, the larva of Trichomyia differs from all other psychodid larvae. It shares with the larva of Phlebotomus the possession of strong, simple, toothed, mandibles devoid of long setae and sensory processes. It also resembles Phlebotomus in the poorly defined epipharynx and premandibles on the labrum, and in the position of the posterior spiracles near the middle of the last segment. The weakly developed mentum of Trichomyia larvae, however, differs greatly from that of Phlebotomus larvae in which the mentum is very strongly developed as a toothed plate.

The material recorded and described in the present paper consists not only of the specimens in the South Australian Museum, but largely an immense number of specimens sent to the writer by Mr F. H. Taylor of the Department of Tropical Health, Sydney. To him, my best thanks are due for the opportunity to examine and describe this material. Types of the new species are in the South Australian Museum and paratypes amongst the material returned to the Department of Tropical Health, Sydney.

1. Sheep myiasis was investigated in certain districts in Ayrshire, Arran and Argyllshire.

2. Larvae from cases of myiasis were collected and bred out in flyproof apparatus.

3. The fly season was found to last approximately from May till September, reaching its height in July and August.

4. The western districts were found to be the most heavily affected.

5. The flies were found to be partial to low-lying, sheltered ground, especially where much bracken was present.

6. The methods of carcass burial were found to be primitive and inadequate. In most of the farms dipping was carried out without sufficient attention to cleanliness and adequate time of immersion.

7. The hibernation of various species of blow-fly was studied. They were found to pass the winter as prepupae, pupation never occurring normally till April or May.

8. Several species of carrion-feeding blow-fly besides Lucilia sericata were found to be causing secondary myiasis, occasionally and in small numbers, in certain districts, mainly in the west. The species involved were: Lucilia caesar, L. illustris, Protophormia terraenovae, Calliphora erythrocephala, C. vomitoria and Muscina pabulorum. Four of these species Lucilia illustris, Protophormia terraenovae, Calliphora vomitoria and Muscina pabulorum have not previously been recorded from sheep. Records of cases in which these flies occurred are given.

Trepomonas Agilis, first described by Dujardin (1841), is commonly found in ponds rich in decaying organic matter, and in infusions. This flagellate was well known to early workers (Stein, 1878; Kent, 1880–2; Bütschli, 1878, 1889; Klebs, 1892; and others), but owing to its rapid movements they had difficulty in studying its structure and counting its flagella. More recently Wenyon & Broughton-Alcock (1924) found a Trepomonas occurring, together with a species of Bodo, coprozoically in a mucous stool from a human being suffering from colitis.

Previous records and descriptions of the fungus known as Acladium castellanii, a human pathogen in the south-east of Asia and Europe and in Brazil, are cited and an account is given of its morphology when studied in culture on organic media.

It is concluded that it is closely related to, and perhaps merely a strain of, the widely distributed Sporotrichum schencki, the commonest cause of human and equine sporotrichosis, and that the term acladiosis as denominating a distinct disease should be deleted.