Our knowledge of the Indian Rhynchobdellid leeches is still in its infancy, and the little that we have, we owe to the researches of Harding, Kaburaki, and Moore. After the publication of the Hirudinea volume by Harding & Moore (1927) in the Fauna of British India Series, Bhatia (1930a, b, 1934, 1939), Chelladurai (1934) and Raj (1951, 1954a, b) have contributed to the systematics of this group. The present work has been undertaken with a view to advancing further our knowledge of Indian Rhynchobdellid leeches. In this work, the neurosomic theory of somite limits launched independently by Castle (1900) and Moore (1900) has been followed in counting the annular composition of somites. This paper, the first of the series, deals with the description of four Glossiphonid leeches, of which three are new to science, while the fourth one is of zoogeographical importance.

Artyfechinostomum Lane, 1915 (type A. sufrartyfex Lane, 1915) is a synonym of Paryphostomum Dietz, 1909 (type P. radiatum Dujardin, 1845). While the general morphology of the two forms is similar and places them both in the family Echinostomatidae, other characters clearly place them in different genera of this family. In Artyfechinostomum the cirrus-sac extends far posterior to the acetabulum, and the right and left fields of vitellaria in the post-testicular region are confluent. In Paryphostomum the cirrus-sac is small and anterior to the middle of the acetabulum and the vitellaria in the post-testicular region are not confluent. These differences entitle Artyfechinostomum to be placed in a separate genus. The species Paryphostomum indicum Bhalerao, 1931 and P. mehrai Jain, 1957 are transferred to the genus Artyfechinostomum.

An account is given of the occurrence of Parabothrium gadi-pollachii and Abothrium gadi in some members of the Gadidae caught in the north-eastern Atlantic.

The external features, musculature, excretory, nervous and genital systems of the two species are described in detail.

The adults of both species are characterized by the absence of a typical pseudophyllidean scolex and possess interesting modes of attachment to the intestine and caeca of the host. The variation found in individuals of A. gadi from the cod and haddock is discussed.

While working on the life cycle of Cercaria mehrai Faruqui, 1930, the author obtained the adults from the intestine of experimentally infected white rats. The trematodes thus obtained were reported as belonging to the genus Paryphostomum Dietz, 1909. In view of the facts that the collar spines are 43 in number, the vitellaria are confluent in the post-testicular region and the cirrus-sac extends far behind the acetabulum, P. mehrai is transferred to the genus Artyfechinostomum Lane, 1915, which is, in author's opinion, a valid genus (Jain, 1959).

The last twenty-five years have witnessed an increasing output of significant work in this country on the trematode parasites of a number of wild birds, including aquatic species. These studies, which are mostly faunistic, and can be said to have commenced in 1926, when Bhalerao (1926) described from Burma (then a province of India) the flukes of the house crow, deal primarily with a large number of representative species of nearly twenty families of Digenea. Of these families, species assignable to the Clinostomidae Lühe, 1901, the Cyathocotylidae Poche, 1926, the Cyclocoelidae Kossack, 1911, the Diplostomidae Poirier, 1886, the Echinostomatidae Poche, 1926, the Notocotylidae Lühe, 1909, the Opisthorchiidae Braun, 1901, and the Strigeidae Railliet, 1919, were encountered in a survey conducted to assess the nature of helminthic infections in wild aquatic birds of the Mathura area.

Azure A, azure B and Nile blue in both neutral and alkaline solutions were found to be suitable for use as indicator dyes in the Sabin-Feldman test. Toluidine blue, brilliant cresyl blue and thionine were also suitable as neutral solutions. Azure C, phloxine, phloxine B, neutral red, methyl green, pyronine Y, eosin and celestine blue were found to be unsuitable. Azure B and toluidine blue in saline solutions were serviceable up to 5 months after preparation. The significance of these findings is discussed.

This account is based upon the study of forty monogenetic trematodes belonging to the genus Calicotyle Diesing, 1850, found in the following hosts, locality and habitats:

When third-stage trichostrongyle larvae exsheathed, they released an exsheathing fluid which eroded the sheath at the anterior end. This led to the formation of a refractile ring and ultimately to the fracture of the sheath which enabled the larva to escape.

Exsheathment was induced by ovine rumen fluid. The exsheathing activity of rumen fluid was impaired by centrifuging, filtering, boiling and aeration, but activity could be restored by the addition of reducing agent. The activity in vitro of either fresh rumen fluid or freeze-dried rumen fluid, after addition of a reducing agent, was comparable with that obtained in vivo.

After stimulation, the process of exsheathment continued in the absence of rumen fluid. The ability of rumen fluid to stimulate larvae was dependent upon temperature, hydrogen-ion concentration and oxidation-reduction potential.

Exsheathing fluid was present in larvae both before and after exsheathment. Larvae which had been stimulated to exsheath released exsheathing fluid for a brief interval and further release could be obtained only after the stimuli had been temporarily withdrawn.

The mechanisms for reception of the stimulus to exsheath and for storing and releasing exsheathing fluid were located in a region between the base of the oesophagus and the excretory pore. The fluid was probably released from the excretory pore.

Exsheathing fluid from one species was not necessarily as active against sheaths from other species as against its own. The activity of exsheathing fluid was dependent upon the presence of a heat-stable cofactor of low molecular weight. Activity of the dialysed fluid could be restored by addition of MnCl2 or MgCl2. Values of Q10 for the action of the fluid on the sheath lay between 1·3 and 1·9. Activity was inhibited by Hg2+, Fe3+ and iodoacetic acid.

1. The availability of Nematodirus infection to sheep was followed by grazing successive pairs of worm-free lambs on a contaminated plot. It was shown that lambs did not become infected during the summer following pasture contamination in the spring, but became infected when they were grazed on the plot the following spring.

2. The development and hatching of the eggs and larval stages of N. battus and N. filicollis were followed by the periodical examination of infected faeces set out during May-November. The results showed that development to the infective larval stage occurred during the summer, taking normally about 3 months, but that the larvae then remained dormant within the egg membranes until the following spring.

3. Laboratory studies confirmed the hypothesis that the hatching of the infective larvae was a response to a rise in temperature in the spring, following sensitization by exposure to low temperature during the winter. A rise in temperature to 50° F. was necessary before a high percentage hatch occurred.

4. The epidemiology of Nematodirus infection is discussed in relation to these observations.

1. Mehlis's gland secretion in trematodes and pseudophyllidean cestodes may be a lecithin-like phospholipid.

2. After enzymic degradation of the lecithin into lysolecithin the release of egg-shell precursors from the vitelline cells is effected.

3. Soon after the completion of the egg-shell the lysolecithin may be reconverted into lecithin in vitelline cells of Penetrocephalus ganapatii, thus accounting for the periodic acid-Schiff positive reaction.

1. Herpetomonas ludwigi was found in 5–6% of larvae of Tipula paludosa in two out of three populations examined.

2. The developmental cycle is confined to the enteric caeca of the host. From a study of smears and sections of these organs it was concluded that the life cycle was composed of the following stages:

(a) A long-flagellated leptomonad stage which is short-lived and probably represents the form in which the flagellate enters the caeca from the mid-gut lumen; (b) a haptomonad or attached form in which the flagellum is short or absent: this probably represents the growth phase of the organism; (c) a crithidial phase which arises by a series of divisions from the haptomonad; (d) a small trypaniform stage which breaks free and lives in the lumen of the caecum; (e) a precystic flagellate; and (f) a small, thick-walled cyst.

3. This species is characterized by its restriction to the enteric caeca and the short duration of free swimming as opposed to attached stages in the life history. This second feature is a corollary of the first. The periodic contraction of the enteric caeca makes attachment obligatory throughout the growth and division stages. These contractions also serve to void cysts into the mid-gut whence they leave the larva with its dejecta to infect other larvae.

The monogenetic trematode Discocotyle sagittata attaches itself to the gills of Salmo trutta with its long axis inclined to the long axis of the primary lamella to which it is attached, the direction of inclination being determined by the incidence of the gill-ventilating current of the host. The inclination is to some extent brought about by an asymmetrical disposition of the posterior adhesive organs, but Discocotyle appears to retain a primitive unspecialized character in that the asymmetrical disposition is facultative and not obligatory and permanent as in Axine.

The adhesive apparatus consists of four pairs of clamps and one pair of hooks. The hooks appear to be the persistent posterior hooks of the larva.

Each clamp is operated by an extrinsic muscle-tendon-fair-lead-hinged-jaws system generally similar but possibly less efficient than the corresponding system in Plectanocotyle gurnardi. Scheuring's and Sproston's interpretations of the clamp-closing mechanism of Discocotyle as a spring system are wrong.

Although the majority of rotifers are free-living, there are many records of rotifers parasitizing both plants and animals (Thompson, 1892; Budde, 1925; Remane, 1929). The most marked development of this parasitic habit is found in the genera Balatro, Drilophaga, Zelinkiella and Albertia. In these forms, with the exception of the genus Zelinkiella, attachment to the host is performed by the mastax. Albertia vermicularis Dujardin (1838) has been recorded as a parasite of the intestine and body cavity of earthworms. This author also found specimens in slugs, but he did not indicate the host species involved in either case. This original description was rather incomplete, and it is the object of this paper to expand it by a description of specimens from Allolobophora caliginosa.

1. The dorsal plate which probably represents a rudimentary scutum in some Argasid larvae is discussed and described.

2. The respiratory system of the larvae of some species of Argas and Ornithodorus is described.

3. The systematic position of the lahorensis group of the genus Ornithodorus is discussed and the use of the name Alveonasus with an emended diagnosis for this group is suggested.

4. Ornithodorus procaviae n.sp. is described. Two other probably new species are described provisionally, but not named.

5. New records for other species of Argasidae in Israel are given.

1. A spring-rise in faecal strongyloid egg count is described in sheep housed under conditions designed to prevent reinfestation. Large rises were observed in the majority of 3-year-old breeding ewes and primiparous ewe-hoggs, and occasional small rises occurred in nulliparous ewe-hoggs and wether-hoggs.

2. Falls were observed in the packed red-cell volumes of ewes during the period of spring-rise and a close inverse correlation was found between packed-cell volumes and transformed worm egg counts. No evidence was obtained to attribute the falls in packed-cell volume to factors other than worm burden.

3. The fall in packed-cell volume was partially alleviated by feeding of one type of perennial rye-grass, but no direct effect of feeding on the worm-egg output was found.

4. Theories of spring-rise are discussed and the conclusion reached that latent overwintering larvae must play a major part generally in the phenomenon.

1. The staining and morphology of E. parvum were characteristic of the genus Eperythrozoon. The diameter of the organism was approximately 250 mμ.

2. Visible eperythrozoa disappeared in 20 min. from infected blood incubated at 56° C., and in 12 hr. at 37° C. They persisted for several days at room temperature.

3. E. parvum was preserved for short periods at 5° C. and for longer periods at −30 and −79° C.

4. Splenectomized early-weaned piglets were experimentally infected by the parenteral and oral routes, and by means of the pig louse Haematopinus suis.

5. The mean prepatent period of 103 primary infections in splenectomized pigs was 9·7 days. Patent infections sometimes persisted for at least 36 days. One pig remained a carrier of E. parvum for 23 months.

6. A severe anaemia occurred in splenectomized piglets affected with E. parvum, but intact piglets were apparently unaffected.

7. E. parvum was susceptible in vivo to neoarsphenamine and oxytetracycline, but not to sulphadimidine, penicillin or streptomycin.

1. Ten strains of Ornithodoros moubata not fed as adults and never mated were exposed to dry air at 32·2° C. and the effect recorded by measuring the loss of weight and survival rates.

2. Two rates of water-loss were found and O. moubata may be divided into three groups on physiological grounds. Strains found in native huts in South Africa differ from all other tested strains by losing water in dry air at 0·16 mg. per day. All other tested strains lost water at 0·32 mg. (range 0·29–0·4 mg.) per day. The wild strains of the East African warthog and porcupine burrows are distinguished from the East African domestic strains by their ability to withstand prolonged starvation.

3. The initial mean weight of a strain in any of the groups has a considerable effect upon survival in dry air, the percentage survival (in 100 days tested) being directly proportional to the original weight of the ticks. Size of individuals could alone lead to ultimate survival differences of two months in different strains of the same form.

1. Observations have been made on the life cycles of Cercaria paracauda, Iles, G. tetraglandis, Iles, and C. Apatemon gracilis minor, Yamaguti. The development of the tetracotyle metacercaria of C. tetraglandis has been followed and also that of the metacercaria and adult of A. g. minor. The pathology and distribution of the metacercariae of the last two species within the leech, Erpobdella testacea (Sav.) has been studied.

2. It was noted that development of the metacercariae within the same host and resulting from the same infection was not simultaneous and that it was improbable that a 100 % encystment of the metacercariae would occur. Temperature was found to have a marked effect on the length of time required for encystment.

3. Data are given on the infectivity and excystation of the metacercariae of A. g. minor and on the biology and morphology of the adult of this subspecies.

4. Stress is placed on the importance, in the systematics of the digenetic trematodes, of considering both the morphological and biological characters of the adult and those of the related larval stages.

In a literature search for species of Pterygosoma it has been my good fortune to find a figure and Japanese description of Pterygosoma japonicum Kishida, 1927, in Figuraro de Japanaj, Bestej Tokyo, 1927, Hokurykan and Co. Ltd. This species has not been listed by the Zoological Record, and indeed it seems to have been completely overlooked in the West. Hence this re-publication.

Rabbit serum containing cytoplasm-modifying antibodies was fractionated by alcohol precipitation at low temperature and controlled ionic strength and pH. The highest cytoplasm-modifying antibody titres were observed in fractions that contained γ-globulin.