The capillariid nematodes present in avian hosts collected in Palawan and Borneo are recorded and described. Three new species are established, Capillaria javanensis from Dinopium javanense everetti, Drycopus javanensis hargitti, Mei-glyptes tukki tukki and Megalaima chrysopogon chrysopsis, Capillaria pitti from Pitta sordida sordida, Copyschus niger niger, Copyschus saularis and Chalcophaps indica indica, and Capillaria anthracocerosi from Anthracoceros marchei. Capillaria tridens and C. madseni are recorded from new hosts.

We wish to acknowledge the field support by Dr D. S. Rabor, Department of Biology, Silliman University, Damaguete City, Negros Oriental, Republic of the Philippines, and the technicians of the Parasitology Department of Naval Medical Research Unit No. 2 for general assistance in procurement and examination of hosts. The authors are indebted to Messrs H. G. Deignan (deceased) and George Watson, U.S. National Museum, Washington, D.C., as well as to Dr Rabor for identification of hosts. Dr B. J. Myers assisted with the initial handling of the spe

Initial work for this study was supported by funding under Public Law 480, Section 104(c), by funds provided by the Bureau of Medicine and Surgery, Navy Department Work Unit MR 005.20–0098, by contract no. NR 103–690/N 0014–66–C 0094, between the Office of Naval Research, Department of the Navy and the Southwest Foundation for Research and Education, and grant no. 5 P01-GM-13252–02 from the National Institute of Allergy and Infectious Diseases, DHEW. Final efforts were sponsored by the Department of the Army, contract no. DADA 17–68-C-8094.

Serum taken between 2 and 3 weeks after infection of the donors with E. maxima conferred a considerable degree of protection against infection with the homologous organism when injected daily into young recipients. Different pools of such sera had differing activities, but the majority gave protection of 50% or more whereas a few were inactive.

The degree of protection obtained was dose-dependent, varying directly with the volume of serum injected and inversely with the size of the challenge oocyst inoculum.

A course of injections started early in the life-cycle had a greater effect than those started in mid- or late cycle even when comparatively large volumes of serum were given.

Protection was species specific; serum obtained from birds infected with E. maxima did not protect against E. praecox or E. acervulina.

The assistance of Mrs Patricia Hesketh is gratefully acknowledged, as is the help of other members of the staff of the Parasitology Department. Mr P. Townsend, Senior Poultry Attendant, supervised the cleaning and sterilization of cages and the collection of faecal samples.

Larval Taenia crassiceps of the ORF and KBS strains have been shown to accumulate whole 14C-Chlorella proteins in the bladder fluid. Precipitation by trichloroacetic acid removed 70% of the radioactivity indicating the 14C-Chlorella proteins had not been catabolized during movement into the bladder fluid.

The fine structure of the macrogametocyte, macrogamete and the early stages in the formation of the oocyst wall of Eimeria acervulina have been described and compared with other species of Eimeria. It has been shown that type II wall-forming bodies are formed in cisternae of the granular endoplasmic reticulum in association with Golgi complexes. The developing oocyst has been shown to be enclosed by three membranes: the outermost is the original membrane of the merozoite and macrogametocyte; the second membrane appears when the wall-forming bodies are appearing in the cytoplasm of the macrogametocyte and the innermost membrane appears after fertilization. The wall-forming bodies discharge their contents between the innermost membrane and the middle membrane.

We wish to thank Mr P. L. Long for much valuable discussion, Mrs B. Fisher for technical assistance and Mr B. Carter for assistance with the photography.

The mature egg and the acanthor of Moniliformis dubius have been redescribed with special emphasis on the features relevant to the locomotion of this larval acanthocephalan. The movements of acanthors have been analysed by the use of frame by frame study of filmed records of motile acanthors. Acanthors appear to use the same mode of locomotion for hatching, locomotion within the gut of the intermediate host and penetration of the host's gut wall. Movement is produced by a set of spiralled, longitudinal muscles in the body wall of the hind body and two rostellar retractor muscles. This musculature acts both directly on the body wall and indirectly by hydraulic effects via the hydrostatic skeleton of pseudocoelomic fluid. The spiny evertable rostellum and the backward facing spines of the hind body are the means whereby shape changes of the acanthor interact with the immediate environment to produce effective progression.

I should like to thank Professor D. Arthur for the provision of laboratory facilities, Dr D. W. T. Crompton for the initial gift of eggs of M. dubius and Mr R. D. Reed for invaluable assistance with microcinematographic technique. The work was carried out during the tenure of a Nuffield Foundation Research Fellowship.

Three male and four female parasites were recovered from the gizzard of a koel, Eudynamys scolopacea Linnaeus (Cuculiformes). In all, about forty birds were examined and only one was found infected. The present account is based on a study of three male and three female specimens, one female specimen being slightly damaged.

African representatives in the family Microphallidae (Trematoda) are recorded, and descriptions of five new species are given. Collections made on the Kenya coast showed: (Aves) Crocethia alba infected with Microphallus kenyensis sp.nov.; Encocotyle africanus sp.nov., and Maritrema sethsmithi sp.nov.; Tringa hypoleucos and Numenius phaeopus infected with Diacetabulum curvicolon Belopolskaia, 1952; (Reptilia, Scincidae) Ablepharus boutonii africanus infected with Levinseniella heardi sp.nov., Maritrema sethsmithi sp.nov. and Maritreminoides ablephari sp.nov.

Patti Hirst and Alma Smith assisted with preparation of the plates. R. W. Heard III and S. Deblock loaned material and made helpful comments on the reproductive structures in the genus Levenseniella.

Erythrocytes of Tropidurus torquatus (Sauria, Iguanidae) infected with Plasmodium (Sauramoeba) tropiduri show acid phosphatase activity in Golgi vesicles, multivesicular bodies, secondary lysosomes and autophagic vacuoles. The functional relations between these structures and exocytotic activity is discussed.

The authors express their gratitude to: Professor A. G. E. Pearse for his helpful criticism of the work and during the preparation of the revised manuscript; to Professor P. C. C. Garnham for his advice and for his provision of facilities. We are also indebted to Mr Ian McLure for his help in translating the original Spanish into English.

The habitat of patients with L. minor infection in Trinidad, Tobago and Surinam is described. Three species of Lagochilascaris are redescribed and compared. A new species from Felis concolor is described and a synopsis, with a key to the genus is provided.

The development of L. minor is described from eggs and larval stages obtained from neck lesions of patients. The developmental pattern through third- and fourth-stage larvae was found to conform closely to that of other ascaridoid species, but the tail of the second-stage larva showed a unique conformation.

The earliest stage of development found in human lesions was the third stage, the smallest larva being 1·8 mm in length. The third moult was observed at about 5 mm and the fourth moult at 8 mm. Adult worms were observed with a minimum length of 5 mm in the male and 6 mm in the female. Eggs were present in some females of 8 mm length.

The observations are discussed in relation to previous concepts concerning the affinities, host specificity and evolution of this group of nematodes.

The writer takes pleasure in acknowledging the considerable help he received in this work from several colleagues and friends: Professor J. J. C. Buckley for sending specimens of L. minor and L. buckleyi from the Department of Helminthology, London School of Hygiene and Tropical Medicine; Drs A. G. Chabaud and Marie-Claude Durette from the Museum national d'Histoire naturelle, Paris for sending specimens of L. major; Dr P. Araujo from the Universidade de São Paulo, Faculdade de Farm´cia e Bioquímica for sending specimens of L. minor; Dr J. F. Teixeira de Freitas of the Instituto Oswaldo Cruz, Rio de Janeiro for sending specimens of L. turgida; Drs M. D. Little and P. C. Beaver from the Department of Tropical Medicine, Tulane University New Orleans, for sending specimens of L. minor and notes on their observations relating to L. minor. Grateful acknowledgement is also due to Dr O. H. Siung of the Ministry of Health, Port of Spain, Trinidad, and Dr Cox, Chief Medical Officer, Tobago, Dr A. H. Jonkers and his colleagues at the Trinidad Regional Virus Laboratory, and to His Excellency Dr B. F. J. Oostburg, Minister of Health of Surinam, for their considerable help and co-operation which enabled the writer to observe patients and examine specimens in Trinidad and Surinam. The able technical assistance of Miss Mary Cremin, Mrs A. McKeown and Mrs A. Green is gratefully acknowledged. Financial assistance for this study was provided under grants from the Australian Research Grants Committee, the U.S. Dept. of Health, Education and Welfare no. A. 107023–02, and the University of Queensland Research Grant.

A dilution medium for the cultivation in vitro of the erythrocytic stages of P. knowlesi has been simplified to contain the following: a balanced salt solution, glucose, isoleucine, methionine, adenosine, p-aminobenzoic acid, biotin and calcium pantothenate. The medium, in the presence of plasma gave better results than the Harvard medium for the growth of P. knowlesi during one asexual cycle and also allowed the subculture of the parasites through three asexual cycles before a reduction in the number of parasites was observed.

We should like to thank Dr F. Hawking and Dr K. N. Brown for their advice and Mr T. J. Scott-Finnigan for technical assistance. One of us (P.I.T.) received financial assistance from the World Health Organization.

The distribution of Tetrahymena limacis in its natural host Deroceras reticulatum, and the tissue responses to infection are described. Contrary to previous observations, T. limacis occurred throughout the tissues and organs of its host; the organisms were especially numerous in the kidney, the mantle shield, and in grossly visible papules on the external epithelium. Aspirates from such papules yielded numerous ciliates.

T. limacis elicited a considerable pathologic response and appeared to contribute to an increase in morbidity and mortality among slugs. Tissue responses were focal (fibrotic encapsulation of isolated organisms) and diffuse (necrosis, mechanical tissue destruction, and metaplasia). Efforts to establish infection in seven species of molluscs other than D. reticulatum were unsuccessful.

An extramolluscan cyst stage of T. limacis is reported for the first time. Both resting and reproductive cysts were observed. Since free-swimming trophozoites of T. limacis are not long lived, the organism is more likely an obligate rather than a facultative parasite of molluscs. Observations also suggest that slugs are infected via the respiratory pore rather than orally.

It is a pleasure to acknowledge the aid and counsel given by Dr J. O. Corliss in identifying the ciliate and to Miss Lorin DuBois for technical assistance.

The effects of P. burrili adults on the chicken host are outlined. There was no evidence that infections of up to 20 flukes caused marked pathological changes in the nictitating membrane to which flukes attach in an intimate 'placental' manner by the ventral sucker.

The food material of adult flukes is largely lacrimal secretion; it appears that blood can be excluded from the diet since the caecal contents are colourless and haemoglobin was not detected histochemically. Little material was detected in the caeca by the histochemical techniques used. The presence of a mucus coat around flukes was noted and it is suspected that materials of nutritional significance may be conserved in this coat for long periods. Glucose was demonstrated in the parenchyma surrounding the uterus. It is suggested that this might indicate either (a) polysaccharide degradation in this region; (b) polysaccharide synthesis; or (c) a site of accumulation of glucose which enters through the tegument and caeca. The presence of greatest activity in the uterine region may be indicative of nutritional dependence of the developing miracidium on the parent fluke.

The gastrodermis of the caeca is regular, consisting of flattened cells with a very prominent PAS positive, striated border of microvilli. The cytoplasm of the cells contains appreciable amounts of RNA. Protease, acid phosphatase and possibly esterase have been demonstrated in the gastrodermis.

Possible esterase activity occurs in the ventral sucker, alkaline phosphatase is present in the lining of the excretory ducts, and acid phosphatase has also been demonstrated in the pharynx, both suckers, and subcuticular region.

Ferritin was ingested by flukes in vivo and this enabled the digestion cycle to be followed. Flukes ingested little or no ferritin in vitro. Digestion was completed within 13 h and appeared to take place in close association with the striated border rather than in the lumen. The possibilities are that (a) material is digested intracellularly within the microvilli; (b) membrane (contact) digestion takes place; (c) extracellular digestion, in close association with the striated border, takes place. These processes are not necessarily mutually exclusive.

I should like to thank Professor J. D. Smyth for his helpful advice. This study was carried out during the tenure of an Australian National University Research Scholarship.

Cestodes collected from birds of El Recreo, Zelaya, Nicaragua are reported. Sacciuterina mathevossiani sp.nov. from Rhamphocaenus rufiventris is the only species in the genus with 32 rostellar hooks, each 22–24 μm long, and with 5–9 testes. Angularella beema (Clerc, 1906) Strand, 1928, from Iridoprocne albilinea, is partially redescribed. Also reported are Dilepis undula (Schrank, 1788) Weinland, 1858, from Turdus grayi; Anomotaenia mutabilis (Rudolphi, 1819) Baer et Bona, 1960, from Florida caerulea; Ophiovalipora lintoni (Olsen, 1937) Coil, 1950, from Butorides viriscens; Hymenolepsis pellucida Fuhrmann, 1906, from Ramphocelus paserinii and Gymnostinops montezuma; and Raillietina (R). maplestonei Southwell, 1930, from Amazona autumnalis. All are new records for Nicaragua.

Thanks are expressed to Dr Thomas R. Howell, University of California who, assisted by Mr John Zeiger, collected and identified the hosts. The collecting of birds was supported in part by a grant to Dr Howell from the University of California Association in Tropical Biogeography. Gratitude is also expressed to Dr W. H. Coil, University of Kansas, who examined some of the specimens and offered helpful suggestions, and to Miss Dorothy B. Segal, Beltsville Parasitological Laboratory, for checking the records on Angularella.

Twenty-one sheep were killed after having been kept for varying times on a pasture contaminated with Haemonchus contortus. The proportions of linguiform A to linguiform B phenotypes were estimated for the H. contortus populations of each sheep. They gave further evidence that the linguiform B phenotype gradually replaces the linguiform A phenotype during the summer. Given the genetic basis of the phenotype it is pointed out that this seasonal change would appear to be inconsistent with any theory stating that essentially only one generation of worms is involved in the yearly outbreaks of disease.

Many studies have been carried out on the structure and chemical composition of trematode and cestode egg envelopes. Among the nematodes, much work has been done on the eggs of ascarids but there have been few studies on the egg envelopes of species in the Superfamily Trichostrongyloidea. Zawadowsky et al. (1929) reported on the biology of five species of this family, namely Trichostrongylus instabilis (T. colubriformis), T. extenuatus (T. axei), T. probolurus, Cooperia pectinata and Ostertagia mentulata. They described the egg envelope as consisting of three or possibly four layers. The physical and chemical properties of these layers were investigated and these workers concluded that the structure of the egg envelope was similar to that of Ascaris. However, the solubility of the inner layer differed from that of Ascaris in dissolving only partially in absolute alcohol and very little in ether.

In an attempt to determine the mechanisms of resistance to schistosome infection operative in bulinid snails, an histological study was carried out on batches of a refractory strain of Bulinus truncatus and two highly susceptible strains of B. africanus killed at various intervals of time, ranging from 7 h to over 3 months, after exposure to infection with Schistosoma mattheei miracidia.

It was found that only a small fraction (less than 1%) of the miracidia penetrated B. truncatus, and that they penetrated only a few of the snails exposed. Much larger proportions (up to 26%) of the miracidia penetrated B. africanus and they penetrated nearly all the snails exposed.

In the susceptible B. africanus only miracidia which settled in the loose tissues of the head-foot proceeded to develop: those settling in dense tissue failed to develop and degenerated within about 2 days.

A strong infiltration reaction of amoebocytes rapidly destroyed the few miracidia that successfully penetrated B. truncatus. In contrast, B. africanus did not respond to the presence of miracidia in its tissues, nor to mother or to daughter sporocysts before the onset of cercarial shedding: it reacted only to cercariae.

It is concluded (a) that the combination of an effective surface barrier and an active defence mechanism due to amoebocytes were responsible for complete resistance to S. mattheei infection in B. truncatus (b) that successful establishment of S. mattheei infection in B. africanus depended on the failure of the snail to recognize the schistosome miracidia and sporocysts as foreign material.

I am indebted to Professor George S. Nelson for advice and encouragement in this work which was carried out at the London School of Hygiene and Tropical Medicine. I am most grateful to Dr R. J. Pitchford, Dr C. A. Wright and Dr F. Arfaa for providing material for schistosome and snail cultures and to the East African Community and the British Ministry of Overseas Development for financial support.