The recorded parasites and predators of Meligethes aeneus (F.) and M. viridescens (F.) [Coleoptera: Nitidulidae] are given together with descriptions and illustrations, for the first time, of the post-embryonic stages of the hymenopterous parasites Diospilus capito (Nees) [Braconidae], Isurgus heterocerus (Thoms.) [Ichneumonidae], Isurgus sp. A, and Cryptoserphus parvulus (Nees) [Proctotrupidae]. The egg and first instar of Thersilochus sp. are described and figured, and a species of Zeteticontus mentioned. The antennae, propodea, and ovipositors of the two species of Isurgus are compared and the ovipositors of Diospilus capito, Isurgus sp. A, I. heterocerus and Thersilochus sp. are illustrated.

A protozoan (Gregarine), a larval mite and a nematode, none of which has been identified, are recorded inhabiting Meligethes adults.

The nematodes described below were collected by M. L. Emanuel from two specimens of the pouched mouse, at Innisfail, North Queensland. They were very kindly sent to the author by Dr M. J. Mackerras of the Queensland Institute of Medical Research. Both species of parasite were present in both host animals. Trichostrongyles have not previously been described from phascogales but a metastrongyle, two spirurids, and a rictulariid, are listed by Dr Mackerras in her check-list of parasites of Australian mammals (Mackerras, 1958). To these may now be added the present records, the details of which are as follows: Phascogale flavipes (Waterhouse, 1838). Innisfail, Queensland. Nicollina phascogale sp.nov., Tetrabothriostrongylus mackerrasae gen.nov., sp.nov.

1. Gametocytes of Plasmodium gallinaceum emerged from the erythrocytes and the male gametocytes exflagellated normally in vitro, in normal or inactivated horse serum, or in rabbit plasma.

2. Gametocytes, washed and suspended in normal horse serum, completed their sexual development and produced oocysts in mosquitoes.

3. Hyperimmune chick plasma, as compared with normal chick plasma, did not significantly affect the time of onset or the frequency of exflagellation.

4. In a solution, isotonic to bird blood and adjusted to approximately pH 8, containing NaCl, KC1, CaCl2, Na2HPO4, MgSO4, NaHCO3 and Tris buffer, the in vitro development of the gametocytes was normal, and the numbers developing were comparable to those in horse serum, or in plasma or serum from the normal host. The development of the gametocytes was inhibited by the omission of Na or HCO3 ions, but the omission of Mg, K, Ca, SO4 or HPO4 ions had no effect.

5. Further experiments showed that the gametocytes emerged from the corpuscles and the males exflagellated normally in a solution containing only Na, C1 and HCO3 ions. Other combinations of ions were tested, but although gametocytes emerged from the corpuscles in some of these solutions, exflagellation either did not take place or did so infrequently, and the gametes produced were feeble in their movements. Within the range of inorganic salts tested, Na, HCO3 and C1 ions constituted the minimal requirement for the normal in vitro development of the male gametocytes.

A holotrichous ciliate found repeatedly in very large numbers in the body cavity of larval midges (Chironomus plumosus) from Paris and Berlin areas is described as a new species of the genus Tetrahymena, named T. chironomi sp.nov. It appears to represent a true example of facultative parasitism, since parasites released from the host survive in laboratory cultures, and free-living ciliates believed identical have been isolated from fresh-water sources in nature. Over a 3-month period more than 2000 larvae, principally fourth-instar stages, were examined; about 9 % of these were found to be infected with ciliates.

T. chironomi is the thirteenth species to be added to the growing holotrich hymenostome genus Tetrahymena. It is taxonomically distinguishable from other members of the genus on the basis of a combination of characteristics related to its morphology and bionomics. It is one of the smallest species, has 24–27 ciliary meridians and a relatively large, spherical micronucleus, does not exhibit dimorphism or cystic stages in its life cycle, and does not possess a caudal cilium.

1. The character of the scolex, the long filamentous neck and the morphology of the proglottids are features which justify the establishment of a new genus, Penetrocephalus, to accommodate the pseudophyllid species P. ganapatii (= Both-riocephalus ganapatii (Rao, 1954), B. penetratus (Subhapradha, 1955)) from the marine teleost Saurida tumbil Bloch, off Waltair, Bay of Bengal.

2. The anatomy of the female reproductive system is described in detail, and a preliminary interpretation of the histochemistry of egg-shell formation is given.

3. On the basis of histochemical tests it is suggested that Mehlis's gland, which surrounds the cellular ootype, secretes a phospholipid-like material which may aid in the release of shell precursors from the vitelline cells, but it does not form part of the shell. It appears also to be responsible for the synthesis of PAS-positive yolky matter found in these cells in the egg capsule. The functions of Mehlis's gland in helminths are discussed.

4. In a majority of helminths where the egg-shell is a quinone-tanned protein, it is considered that it is solely if not entirely derived from shell globules in the vitelline cells.

The infectivity and invasiveness of a single strain of Entamoeba histolytica to young rats has been studied over a period of 12 years. The virulence was slowly lost over a period of months or years of cultivation in vitro. After four to six liver passages, virulence was again established and again declined in culture. This was repeated on three occasions. Each time the strain lost virulence, the capacity to invade the mucosa was lost before the amoebae became non-infective to young rats. The duration of experimentally acquired virulence was progressively reduced after each succeeding series of liver passages.

1. Four stages in the development of Choanotaenia crassiscolex are described with the help of five text figures and one plate.

2. The functional anatomy of the cysticercoid is given with the help of diagrams.

3. The identification is based on comparisons with material at the British Museum of Natural History, South Kensington, London, and comparison is made with earlier records in Table 1.

4. The unusual cyclophyllidean scolex is discussed and tentative suggestions and queries concerning the general form of the early cysticercoid are put forward.

5. An attempt is made to determine more precisely than has hitherto been done for cysticercoids, the relationship of parasite and host.

Iron-59 (as a ferric chloride solution or as a component of haemoglobin) was introduced into the lumen of the gut of Fasciola hepatica. It was detected by autoradiography in high concentrations in the intestinal epithelium, the cuticular epithelium, the myoblasts and the cells forming the walls of the excretory tubules. Carbon-14, introduced as l-phenylalanine-C-14, was concentrated in the same tissues, with the exception of the intestinal epithelium. These findings are discussed in relation to the function of the respective tissues.

The development of Carmyerius exoporus Maplestone in the snail Anisus nata-lensis Krauss is described with the emphasis laid on the redial and cercarial productivity of the rediae of the first and subsequent generations.

The miracidium gives rise to one sporocyst. From 25 to 32 germinal cells present in the miracidium, only six to eleven develop into embryo balls in the sporocyst and, of these, only three to nine develop into rediae of the first generation.

The redia of the first generation gives birth to daughter rediae and cercariae. No alternation in the development of redial and cercarial embryos was noted in the rediae of C. exoporus and a small number of redial embryos was observed to develop alongside the more numerous cercarial embryos throughout the life of the first generation rediae.

The rediae of the second and subsequent generations also give birth to daughter rediae and cercariae.

The cercariae leave their parent redia when they are still immature and continue the development in the snail tissue.

1. The formation of Opalina cysts in Rana temporaria was compared, during September to December, in groups of untreated frogs exposed to normal seasonal fluctuations in temperature, and treated frogs kept at room temperature. Cyst formation was enhanced, to the same degree, in frogs injected with saline or chorionic gonadotrophin (Pregnyl), and, to a higher degree, in frogs injected with frog pituitaries.

2. Observations were made, during September to December, on the state of the testes in Rana temporaria infected with Opalina. The presence of Opalina cysts was most closely correlated with spermiation.

3. Possible factors affecting the formation of opalinid cysts are discussed. It is concluded that the seasonal production of cysts by Opalina is not due to cyclical changes inherent in the protozoa. The factor or factors provoking encystation appear to be correlated with the reproductive cycle of the host, and may be the gonadal hormones.

1. The tracheal systems of first, second and third instar larvae of Gasterophilus intestinalis are described.

2. The homologies of the conical tracheae of the tracheal organ are demonstrated and explain the apparent disappearance of a complete tracheal metamere.

3. Anomalies in the tracheal system of the anterior segments of Gasterophilus led to an investigation of the tracheal systems of Drosophila, Eristalis, Calliphora, Scatopse and Aëdes.

4. The anterior tracheal system of larval Diptera has been re-interpreted; that of the Cyclorrhapha can be derived from that of the Nematocera without the formation of new tracheae other than a large trachea from the lateral longitudinal trunk to the antero-lateral musculature.

A new species of Amplicaecum is described from the carpet snake (Morelia argus variegatus) in coastal Queensland. It differs from all previously described species in this genus in that its host is a pythonid snake. It is the largest species yet described, and the spicules are about 3 times as long as in any other species. The genus Amplicaecum is tentatively re-defined and a key is given to the differential features of the recognized species. The view is expressed that before classification of these and related ascaridoids can be adopted, further information is necessary, particularly on (1) the phylogenetic significance of differential features already in use, and (2) on the existence of other more significant differential features.

1. Ixodes auritulus group of ticks and Ixodes percavatus group of ticks are both characterized by having the palpal article I drawn out to a horn anteriorly, but in the percavatus group there is a strong meso-dorsal ‘spur’ on this article, which is lacking in the auritulus group.

2. The mutilated types of I. auritulus and I. percavatus sp. revocata are re-described and electotypes established for both.

3. Variations from I. auritulus sensu stricto are described from Peru and Guatemala, and a revised description given of the male, female and nymph from Snares Island.

4. I. percavatus and I. zumpti sp.nov. have been diagnosed from material from Nightingale Island, Tristan da Cunha. Ticks from Marion Island are identified as a new species, I. pterodromae. Female and nymphs from the Paris Museum originally identified by Neumann as I. auritulus now fall into the percavatus group and are named I. cornuae sp.nov.

1. It has been observed that the larvae of four species of chironomid midges invade and destroy the contents of the egg masses of Bulinus (Physopsis) globosus in Amani lake, Tanganyika.

2. There was no indication that this type of predation exercised any restraint on the density of adult snails.

André & Colas-Belcour (1942) described the male of Ixodes kerguelenensis as a variety of I. canisuga on the basis of one specimen. Subsequently Zumpt (1952) stated that its status as a full species was unquestionable, for, compared with I. canisuga, the jugular plates on each side of the pregenital plate in I. kerguelenensis are large. The structure of Haller's organ also fully justifies this separation (Arthur, 1956). Zumpt wrote further that: ‘The specimen on which the authors based kerguelenensis was probably fully engorged so that the ventral plates would be widely separated from each other…. The single male from Kerguelen is drawn as having the anal groove diverging, but this is certainly due to a distortion of the engorged tick.’ Through the courtesy of Professor André I was permitted to examine the type. Distortion is not due to engorgement, as Zumpt suggests, but to the mounting of the specimen on a slide under a cover-glass.

Lipid material occurs in the oocysts of Plasmodium in the form of small Sudano-phil granules, which appear to increase in size with the growth of the parasite. A diffuse Sudanophil material also appears at a later stage.

Phospholipid occurs at a certain stage of the oocyst, but later disappears altogether. It appears more quickly in some oocysts than in the others, found in the same infected gut.

The pre-erythrocytic schizonts of P. cynomolgi are found to contain abundant lipid material.

The erythrocytic stages of Plasmodium and Hepatocystis cannot be stained with the Sudan dyes, but the gametocytes of Hepatozoon infecting the blood corpuscles of the vertebrate hosts are found to contain abundant Sudanophil material.

Sudanophil material can be detected in the unsporulated oocysts of Eimeria stiedae, but not in the sporulated ones.

Glycogen proved to be absent in the malaria parasites (Plasmodium and Hepatocystis) by applying cytochemical methods; while in the piroplasms (Theileria and Babesia), and in Hepatozoon glycogen could be demonstrated by using the same methods. A strong positive reaction for polysaccharides was obtained in the residual masses of Hepatozoon sciuri, and H. balfouri; while a negative reaction was obtained in the residual mass of Plasmodium. A positive reaction for polysaccharides was obtained in the following structures: the wall of the oocysts of Plasmodium, the gametocyte capsules of Hepatozoon sciuri and Hepatozoon sp., the sporoblast capsule of H. sciuri, and the polar areas of the gametocyte of H. balfouri.

Studies on immuno-conglutinin levels in animals infected with T. brucei have shown that immuno-conglutinin appears in rabbits infected with T. brucei ‘M’ variant within 7 days after infection and reaches its peak titre within 30 days. In rabbits infected with the more virulent ‘R’ variant immuno-conglutinin levels rose more rapidly and reached peak titres within 10–14 days after infection.

High levels of immuno-conglutinin are detectable in the sera of rabbits and cats infected with trypanosomes before a significant amount of neutralizing antibody is produced. This difference is most marked in animals infected with the antibody-resistant variant ‘R’ which is more virulent for rabbits.

In animals treated effectively the immuno-conglutinin level dropped to its pre-infection level, while the titre of neutralizing antibody only decreased to a slightly lower level.

No change in the titres of immuno-conglutinin and neutralizing antibody was observed after treatment of animals infected with a drug-resistant strain.

These results are very promising for further field trials and introduce a new approach and method for testing the efficiency of chemotherapy in trypanosomiasis.

Females of Hammerschmidtiella diesingi can survive in the hind-gut of moulting Blatta orientalis. After a period of shrinkage they recover their normal length within 24 hr. in 0·2 and 0·3 m sodium chloride and in 50% sea water, but not in hypotonic media or in hypertonic sucrose. Females of H. diesingi, which have regained their original length in hypertonic media, swell when placed in normally isotonic media; a similar phenomenon occurs with nematodes taken from moulting cockroaches.

1. Trypanosomes were found in the blood of thirty-five of seventy-two fish of five genera (chiefly Tilapia spp.) from Lakes Victoria and George, Uganda.

2. The trypanosomes, which were never numerous in the blood, showed two morphological forms—small (22–44μ. long) and large (45–65μ). No significant differences were observed between the trypanosomes from the different species of fish, and all the trypanosomes seen are provisionally identified as Trypanosoma mukasai Hoare, 1932.

3. Crithidia were found in the gut of a glossosiphoniid leech which had been removed from a fish; although suggestive, this cannot be taken as conclusive evidence that leeches of this family are vectors of T. mukasai.

4. The taxonomy of the trypanosomes of African fresh-water fish is reviewed, and it is concluded that only the following species should be regarded as valid at present: T. toddi Bouet, 1909, T. mukasai Hoare, 1932, and T. tobeyi Dias, 1952.

5. Dactylosoma mariae Hoare, 1930, was found in the blood of thirty-six of the seventy-two fish examined. Merozoites, schizonts and gametocytes of this small unpigmented parasite were observed within erythrocytes. No developmental stages were found in certain viscera of two infected fish.