1. Rana clamitans of New York and R. pipiens from the middle part of the United States, were found to be infected by a Myxosporidian, apparently identical with Leptotheca ohlmacheri (Gurley) Labbé, found by Ohlmacher in the kidney of Bufo lentiginosus.

2. The Myxosporidian was found only in the space between Bowman's capsule and the glomerulus of the Malpighian body and in the uriniferous tubules of the kidneys of the host, no other organ being infected.

3. The mature spore contains two independent uninucleate sporoplasms which fuse into one prior to the germination in the posterior region of the stomach or duodenum of a new host.

4. The germination of the spore was observed in hanging drop preparations with the digestive fluid.

5. The youngest stage found in the lumen of the tubule of the kidney, was the uninucleate form.

6. The trophozoites multiply actively by a process of gemmation and probably also by a schizogony of the uninucleate forms.

7. The trophozoites are, as a rule, disporous and the spores develop independently of each other.

8. The vegetative nucleus persists throughout the entire trophic life of the individual.

9. The Myxosporidian does not exercise any fatal effect upon the host.

10. Infection takes place through the mouth. The liberated binucleate amoebulae probably penetrate through the wall of the small intestine, reach the coelom and are carried to the uriniferous tubules through the nephrostomes or blood vessels.

1. Cyclical development of Spirochaeta duttoni in lice was observed in seven experiments. In the last four, the same strain was transmitted through four successive batches.

2. The resultant infections in animals behaved exactly like S. duttoni even after the fourth transmission through the abnormal host.

Among the Sporozoa inhabiting the gut of Scolelepis fuliginosa Claparède at Plymouth, I have often found an organism that I believe to be a peculiar coccidian, although certain important stages in the sexual part of the life cycle have hitherto escaped me. If I am right in my opinion, then this sporozoan is a new form, belonging to no genus of coccidian hitherto described: I propose for it the name Dorisiella scolelepidis.

Specimens of Notocotylus attenuatus were examined in life and their ventral papillae studied by scanning and transmission electron microscopy. It was found that the papillae are non-secretory, very mobile and similar in ultrastructure to the papillae of other notocotylids previously described. Worms were removed from the host's caecum and the caecum surface examined where it had been in contact with the papillae; this revealed that the crypts in this region had been distorted and enlarged. It is suggested that the papillae serve to attach the worms to the distinct surface of the distal caecum by acting as hydraulically operated anchors working in conjunction with the lateral margins of the worm and allowing the oral sucker of this monostome fluke to be used for feeding.

The fine structure of the shell formed round developing zygotes of an acanthocephalan has been described and compared with the descriptions from light microscopy. The origin of layer 1 from globules in the ovum has been postulated and a sequence of elaboration of the three shell layers has been suggested. The layers of the shell should continue to be numbered rather than labelled with descriptive terms until their origin and chemical composition have been established.

I should like to thank the Avon and Dorset River Authority for collection of the fish.

The development of Paramphistomum sukari Dinnik in a snail host is described with the emphasis laid on the succession of redial generation.

The sporocyst gives birth to about twenty to thirty rediae. These rediae of the first generation commence with the production of daughter rediae then enter the second phase of their productivity during which they produce cercariae. The daughter rediae, or the rediae of the second generation, repeat these two phases during their lives, commencing with redial production and after that changing to the production to cercariae. Both the first- and second-generation rediae are able to produce a few daughter rediae at the end of their life. There is evidence that the subsequent generations of rediae are also able to give birth to daughter rediae and cercariae.

As a result the successive generations of rediae maintain the infection in an intermediate host for a long time, probably as long as the infected snail can survive.

Two ascaridoid nematodes occurring in rodents in South-East Asia, namely Porrocaecum ratti and Toxocara mackerrasae, were compared; the former was redescribed. These and other ascaridoid species occurring in rodents were classified and it was suggested that relative to the other mammalian orders, the rodents are well endowed with ascaridoids. There is, as yet, insufficient evidence for conjecture as to whether species occurring in rodents represent primitive forms from which the species occurring in predatory animals may have been evolved through host—succession—extension, or whether they have been secondarily derived through loss of a predatory definitive host through host—succession—reduction.

Normal and T-cell deprived mice have been compared in their response to infection with Schistosoma bovis. The deprived mice survived longer than comparably infected, immunologically intact controls, despite an increased longevity of the adult S. bovis worms in the former animals giving rise to higher tissue egg densities. The reduced pathology in deprived mice was due to inhibition of T-cell dependent granuloma formation around tissue-bound schistosome eggs, with concomitantly decreased tissue disruption as evidenced by smaller spleens and lower circulating transaminase concentrations. These observations on S. bovis contrast with the greater morbidity and earlier mortality induced by S. mansoni in T-cell deprived mice, the latter due to an hepatotoxic potential of S. mansoni eggs that is expressed in the absence of the host immune response. The absence of hepatocyte damage around S. bovis eggs in deprived mice indicates that this schistosome lacks such a toxin, and this could explain why during S. bovis infection synthesis of the two acute-phase proteins, complement C3 and serum amyloid P-component (SAP) here seemed less T-dependent than has previously been found during S. mansoni infection of mice. In a time-course experiment the hypergammaglobulinaemia induced by S. bovis, and the specific IgG antibody response against egg antigens were significantly T-cell dependent during the early stages of patency. Similarly, in most experiments assayed once between 9 and 11 weeks after S. bovis infection, deprived mice had significantly reduced hypergammaglobulinaemias, and reduced specific IgM and IgG antibody responses against both worm and egg antigens.

Amongst the collections of mites that have been sent to me for identification I have recently found six new species which are described and figured in the present paper.

Neither phosphagens nor phosphagen phosphotransferase activity could be detected in Fasciola hepatica, Hymenolepis diminuta, Moniezia expansa or in the plerocercoids of Ligula intestinalis. The plerocercoids of Schistocephalus solidus, however, possess an active taurocyamine phosphotransferase, although it too contains no detectable phosphagens. The taurocyamine phosphotransferase of S. solidus has an absolute requirement for a divalent metal ion and ATP could not be replaced by ITP, GTP, CTP, or UTP as the phosphate donor. The role of phosphagens in helminths is discussed.

Homogenates of adult Schistosoma mansoni contain enzymes which are capable of transferring [14C]mannose from GDP[U-14C]mannose to a lipid acceptor which migrates as a single peak on a silica gel thin-layer plate. This lipid may belong to the class of polyprenol monophosphates which are intermediate elements in the glycosylation of nascent proteins. The schistosome mannosyl transferase activity is associated with membranous particles and is dependent on the presence of Mn2+. However, other divalent metals such as Mg2+ or Ca2+ can, in decreasing order of efficiency, replace Mn2+. When UDP[U-14C]glucose was incubated with the homogenates in the same conditions, relatively little label was transferred to the lipid acceptor. Live worms incubated in a medium containing GDP[U-14C]mannose seem to incorporate the label preferentially on the tegument and on adjacent subtegumental structures. By adding foetal calf serum to the medium, incorporation of the label can be stimulated.

A large number of the trypanosomes and allied flagellates are now known to be the causal agents of some of the most fatal diseases of man and of the lower animals. The study of these parasites during the past fifteen years has truly made phenomenal strides, and at the present time it holds a position of commanding interest. Novy (1907) in a recent paper aptly states the reason for this active research when he says, “It is not merely because six or seven of these diseases have been recognised in domestic animals in Asia, Africa and South America. It is not wholly due to the discovery of a human form of the disease, but rather to the fact that the mastery by man of whole regions is called into question. The successful contest with malaria and yellow fever has now given place to the fight with trypanosomiasis and upon the issue of this struggle depends to a large extent the destiny of Equatorial Africa.”

In order to investigate the mode of action of a new class of schistosomicides, the N-alkylaminoalkanethiosulphuric acids, the ‘outer 35S] 2-[(1-methylpropyl)amino]-1-octanethiosulphuric acid was synthesized. Labelling studies of adult Schistosoma mansoni were performed in infected mice and in in vitro incubations. After a single oral dose of the drug to infected mice, 5 metabolites were detected by thin-layer chromatography in organic extracts of male and female adult schistosomes. In vitro studies showed that the same compounds were present in organic extracts obtained from adult male and female worms. One of these metabolites was identified by mass spectroscopy as being the dimeric disulphide derivative of the parent labelled thiosulphuric acid.

The disease known as Turning Sickness was first recorded by Mettam (1934) in this journal and later more fully described by Mettam & Carmichael (1936).

The condition has been defined as a protozoan encephalitis of cattle and one of the most striking features of the disease is the demonstration of schizonts indistinguishable from those of East Coast fever in the cerebral lesions of affected animals.

An investigation of the carbohydrate energy metabolism of Rhabdias bufonis, the lung-dwelling nematode parasite of the African toad, Bufo regularis, indicates that the nematode stores very little glycogen (0·137 ± 0·003% on a fresh weight basis) but does utilize oxygen in vitro. The intracellular distribution and high levels of activity observed for the enzymes phosphoenolpyruvate carboxykinase, pyruvate kinase, lactate dehydrogenase, malate dehydrogenase, malic enzyme and fumarate reductase suggest two alternative pathways of carbohydrate energy metabolism.

This contribution is intended to be the last of this series. As one who may claim to have revived interest in these crustaceans from this region since the days of Bassett-Smith just prior to the beginning of the century, I find it particularly gratifying that several Indian zoologists are now steadily engaged in adding to our knowledge of these forms. Altogether some forty-three genera containing about 120 species have now been recorded from the Indian Ocean. This must form only a small fraction of the total number of forms that actually occur on the wide variety of hosts inhabiting this region.

1. The structure of the proboscides of the larva of Dibothriorhynchus grossum (Rud.) is described. Each proboscis is provided with four sets of extrinsic muscles, and there is an anterior dorso-ventral muscle mass connected to all four proboscides.

2. The musculature of the body and scolex is described.

3. The nervous system consists of a brain, two lateral nerve cords, two outer and inner anterior nerves on each side, twenty-five pairs of bothridial nerves to each bothridium, four longitudinal bothridial nerves connecting these latter before their entry into the bothridia, four proboscis nerves arising from the brain, and a series of lateral nerves supplying the lateral regions of the body.

4. The so-called ganglia contain no nerve cells, these are present only in the posterior median commissure which is therefore the nerve centre.

The obligate intracellular protozoan parasite, Toxoplasma gondii exists as 2 life-cycle forms in intermediate hosts. The rapidly dividing tachyzoites responsible for acute disease, present in the first 14 days of infection, give rise to slowly dividing bradyzoites that reside in tissue cysts. Reactivation of disease is associated with conversion of bradyzoites to tachyzoites. A sensitive method for detection and assessment of the number of each life-cycle stage would be useful for following these events. Herein we describe the construction and validation of a plasmid (pSWITCH) containing a polycompetitor construct (SWITCH) for use in competitive reverse transcriptase-PCR (cRT-PCR). pSWITCH contains competitors for SAG2A and LDH2 genes, which are exclusively expressed by tachyzoite and bradyzoite stages respectively, and for β-tubulin, a gene expressed by both stages. Using cRT-PCR, samples can first be accurately normalized for expression of the housekeeping gene, β-tubulin and then the relative levels of SAG2A and LDH2 expression compared to follow stage conversion. The abundance of transcripts for other genes of interest can then be followed during this process as demonstrated here for the SAG2-related family of genes. This technique offers a powerful tool for studying the processes involved in tachyzoite and bradyzoite interconversion.

We compared a Trypanosoma cruzi clone unable to infect or induce pathology in mice (CL-14), with virulent T. cruzi (Y and CL strains) in terms of cruzipain expression, subcellular distribution and functional activity. Our results showed that (1) intracellular Y amastigotes expressed R1 (carboxy-terminal) and R2 (catalytic) domains concentrated in cytoplasmic vesicles, while CL-14 presented R1 labelling on membrane clusters and R2 in intracellular compartments, (2) CL-14-trypomastigotes presented R1 and R2 staining preferentially on flagellar and cellular membranes, similar to CL, but different from Y strain intracellular labelling pattern, (3) flow-cytometry revealed higher expression of R1 by CL-14-trypomastigotes than virulent strains, but R2 staining similar to CL-trypomastigotes, (4) CL-14-trypomastigotes presented normal cruzipain activity in gelatin gels, but different banding patterns were found in CL-14 versus CL and Y strains. Our data rule out failure in cruzipain expression, activity or subcellular distribution as an explanation for CL-14 biological behaviour, but suggest the expression of a different isoform. These results also cast doubt on the putative role of cruzipain as a target of immunopathological responses, since high levels of functional cruzipain are expressed by a non-pathogenic T. cruzi.

During the period 1913–16, I conducted a Survey of the Agricultural Zoology of the Aberystwyth Area, for which purpose the University authorities received a grant from the Board of Agriculture. The area thus examined comprised N. Cardiganshire and some adjacent borders of Montgomeryshire, roughly about 250 sq. miles. It falls into three main physical divisions:

I. The mountainous upland (or high plateau) of solid rocks frequently covered by a considerable depth of peat. The rock succession is only irregularly exposed in deep stream cuttings, while these valleys are occupied by boulder clay and river deposits.

II. The surface of the coastal plateau shows exposures of rock and of boulder clay. The clay is usually exposed and rarely covered with peat.

III. The fall line, which is intermediate. Here the boulder clay generally follows the valleys, and it is usually covered with a thin layer of peat. Much of this is readily cut through by small streams.