In the preceding paper Howard (p. 665) has given a very elegant presentation on ways in which the host immune system may be manipulated to provide valuable information about immunoregulation of parasitic infection in vivo. In our laboratory we have used some of the same manoeuvres to study immunoregulation of genetically controlled responses to Leishmania donovani infection in inbred mouse strains (Ulczak & Blackwell, 1983; Crocker, Blackwell & Bradley, 1984). As has been Howard's experience, the results obtained have not always been as one might have predicted at the outset.

A condition with a weak genetic component, but a strong correlation with age, is the summarizing of conferences. It is an art form often resembling the expression of gratitude by a bride on the receipt of her sixth electric kettle. However, our gratefulness now is genuine, because we have been given a wonderfully interesting series of papers. Their authors were chosen with skill to show the manifold variety of genetic interactions between parasites and hosts. The range of these interactions would daunt even the strongest-hearted summarizer, and my task can only be managed by a ruthless subjectivity.

In a previous paper (Sinha, 1954), dealing with a collection of larval trombiculids from Manipur, India, four new species, a new subgenus (Plumosicola), and a new genus (Mehracula) were described. The larvae concerned had been mounted in batches, each slide containing considerable numbers. At the request of Dr J. R. Audy, Institute for Medical Research, Kuala Lumpur, the type material was lent to him in 1956 through the kind co-operation of Dr A. P. Kapur, in charge of the Entomology Section, Zoological Survey of India, Calcutta, in whose care the types had been deposited, and who gave permission for the specimens to be remounted individually in PVA-mountant.

During the early years of this century, several new species of ticks were described from Western Australia, but since then the group has been neglected, with the result that no species have been added since 1909. In the course of some recent studies of the local ticks, an undescribed species of the genus Ixodes was obtained, of which a description is now given.

Evidence has accrued to indicate that host defence mechanisms enhance the efficacy of many of the drugs used to treat infectious diseases. Because of this, and also because of the likelihood of increased pathogen loads in immunoincompetent hosts, some infections are less likely to be completely cured by normal regimens of chemotherapy in individuals with drastically impaired immune responsiveness. In such circumstances natural selection could result in the accelerated emergence of drug-resistant pathogens.

The humoral responses of Sprague–Dawley rats infected with Brugia pahangi were examined for up to 6 months after infection by ELISA, immunoblotting, and IFAT. In 2 experiments, 50% and 62·5% of rats developed patent, microfilaraemic infections. Mean adult worm burdens at autopsy were approximately 2% of the inoculum, and only patent rats yielded living adult worms. IgG antibody levels against crude somatic extracts (CSE) of all parasite stages and against adult excreted/secreted (ES) products were significantly higher in patent than non-patent rats. Both patent and non-patent rats produced anti-microfilarial surface antibody, as revealed by immunofluorescence. Immunostaining of Western blots by early infection sera showed no consistent difference in recognition of infective larval (L3) antigenic components by IgG or IgM antibody between eventually-patent and eventually-non-patent rats. By 26 weeks, however, patent rats recognized more components. The data suggest that antibodies against L3, adult, and microfilarial somatic antigens, ES antigens and microfilarial surface antigens do not correlate with the subsequent development of microfilaraemia in any individual rat.

In 1916 Dr J. C. Becker made the interesting discovery of Bilharzia infection in Physopsis africana collected at Nijlstroom in the Transvaal and obtained the adult flukes in some guinea-pigs he had exposed to infection with the cercariae. The town of Nijlstroom is situated at the source of a tributary of the Limpopo river at an altitude of 3924 feet above the Indian Ocean into which it flows. In 1917 I collected2 infested examples of P. africana at Magaliesburg, a popular picnic place for Krugersdorp residents, situated on a branch of the Little Crocodile river which later joins the Limpopo. Magaliesburg has an altitude of 5000 feet above sea-level. I also obtained infested examples from Rustenburg, thus revealing a further source of infection from tributaries of the Little Crocodile river, at an altitude of over 4000 feet.

The life history of Ornithodoros graingeri under laboratory conditions at 28° C. and 95% humidity, can be summarized as shown in Table 4. These figures, except for the fourth-stage nymphs, include the interval between emergence and willingness to feed.

Fertilization phenomena has been observed in the malaria parasite of the Himalayan Flying Squirrel with blood showing heavy infection. The blood was obtained on the slide, put in the moist chamber, dried and stained. Two types of microgametes could be distinguished. One of these two types were found in various stages of the process of fertilization. More than one microgamete were often found to take part in fertilizing a single macrogamete. This is the first recorded case of polyspermy in malaria parasites.

Thanks are due to Mr Nandalal Pau for his help in preparing the Plate incorporated in this paper.

This investigation received financial support from the World Health Organization.

Host and Record. At least four specimens of the parasite were found attached to the sides and belly of a sail-fish Histiophorus gladius Day caught off the south coast of Ceylon. I was fortunate enough to obtain two of these, both females, complete except for the egg strings. They measured 135 mm. and 157 mm. in their total lengths. One of them, the smaller, is illustrated in Fig. 1.

The Chalcidoid wasp, Bairamlia fuscipes, was found parasitising the flea Ceratophyllus wickhami in the nest of the North American Grey Squirrel (Sciurus carolinensis) from Gerrard's Cross.

The larval and pupal stages of B. fuscipes were found in the cocoons of C. wickhami, and the adults were crawling about in the squirrel's nest.

The parasites were scarce, only 7 per cent, of the cocoons dissected at intervals during fifteen months were parasitised.

The parasite has not been reared in the laboratory beyond the second instar larva, though full grown larvae have successfully reached maturity under experimental conditions.

B. fuscipes oviposits through the flea cocoon and fixes the egg on the abdomen of a resting larva or pupa. Only one egg has been found in each parasitised cocoon. The larva feeds externally on the flea, fixing itself to the fourth abdominal segment or thereabouts.

Attempts were made to parasitise larvae of Xenopsylla astia, but without success.

The external anatomy of the full grown larva of B. fuscipes is described.