Anthobothrium auriculatum (Rud.) is often referred to as ‘an insufficiently known species’. Southwell (1925) states that ‘all that is known about this doubtful species is contained in Rudolphi's brief description, which is quite insufficient to diagnose the species with, certainty’. Rudolphi (1819) first described it as Bothriocephalus auriculatus from Torpedo marmorata Risso; it is possible that this brief and inadequate description included several species. Leuckart (1820) described what has since been regarded as the same species under the name of Bothriocephalus flos from Carcharinus glaucus (L.), Bremser (1824) gave a brief account of Bothriocephalus auriculatus, and Zschokke (1888) gave a somewhat fuller account of Anthobothrium Auriculatum from Torpedo marmorata. As far as can be judged all these forms are synonymous. Diesing (1850) described what he thought to be Rudolphi's species, placing it in the genus Tetrabothrium; he obtained it from Torpedo marmorata Risso, Hexanchus griseus (Gm.), Carcharinus glaucus (L.), Squatina squatina (L.), and Raja calvata L. It has been pointed out by several writers that Diesing's Tetrabothrium auriculatum does not agree with Anthobothrium Auriculatum (Rud.), because, among other things, the genital pores in the former are anterior and in the latter posterior. Southwell (1925) states that Beauchamp is of the opinion that Tetrabothrium auriculatum Dies, is synonymous with Phyllobothrium gracile Wedl., an idea which is now generally accepted. Joyeux & Baer (1936) recorded Anthobothrium Auriculatum (Rud.) fairly frequently in a number of host fishes, namely, Mustelus mustelus (L.), Scyliorhinus caniculus (L.), Lamna cornubica (Gm.), Eugaleus galeus (L.), Squatina squatina (L.), Carcharias glaucus (L.), Torpedo marmorata Risso, and Raja clavata L. They, too, refer to the species as imperfectly known, and suggest that it might be synonymous with some other species of the same genus. In view of the lack of an adequate description of Anthobothrium Auriculatum it was felt that an account of its anatomy would render future identification of the species simpler and would settle the question as to whether or not it was synonymous with some other known species.

The genus Androlaelaps was raised by Antonio Berlese in 1903 for those Laelaptidae in which leg ii of the male and female is furnished with spurs on the femur, genu and tibia. Amongst the mites taken on a Uganda unstriped grass-rat (Arvi-canthis abyssinicus rubescens Wroughton), numbers of two new species of this genus were found and are here described under the names Androlaelaps oudemansi and A. arvicanthis.

A method is described for the detection of anthelminthic potency. The procedure does not call for exceptional technical skill, is relatively economical of drugs and living material alike, and is rapid and convenient in application. It has certain limitations such as are inherent in any in vitro method, and a special limitation in that it is not applicable to the study of drugs which act otherwise than on the neuro-muscular mechanisms of nematodes. Within these limitations it responds to compounds of known anthelminthjc efficiency and shows little or no response to compounds known to be devoid of anthelminthie value. Approximate quantitative data can be obtained with its aid, the reactions provoked by a given drug are substantially the same in different individuals, and each test provides a visible record of the influence of the drug under examination.

We do not claim that this procedure can in any sense replace experiments upon infested hosts, but must rather be followed up by such experiments when a promising degree of anthelminthie potency has been detected with its aid. We do, however, believe that it has a very real usefulness within the field to which its application is limited. As a preliminary device which allows the selection of promising compounds from large groups of new synthetic products it has already demonstrated its value in tests carried out in this laboratory on a series of about fifty new compounds prepared by Prof. Friedmann.

Some account is given in this paper of certain nematodes obtained by Prof. G. E. Gates from the coelomic cavities of various species of earthworms from South India, Assam and Singapore. The material was kindly submitted to the writer by Prof. Gates in 1936, 1937 and 1939. Of the forms included in it several were represented by specimens insufficient or unsatisfactory for adequate description, and it has seemed advisable to deal only with those species of which a reasonably full account can be given. Of these there are seven, all of which are thought to be new. Four of them can be assigned to a known genus, Synoecnema de Magalhães, 1905; the other three probably represent as many new genera.

It has been known for a long time that certain species of Mallophaga attach themselves to hippoboscid flies, the act taking place on the bird host. This has been referred to as Phoresy, ‘a type of interrelationship between insects in which one is carried on the body of another larger insect, but the former does not feed on the latter’, or, in other words, free passage without food.

1. Worms which had been cultured in media of different osmotic pressures were immersed in concentrated solutions of NaCl, KC1, CaCl2 and MgCl2, and the times of cessation of spontaneous movement noted.

2. Worms from ‘normal’ cultures were immersed in a single concentration of each of the above solutions (all osmotically equivalent to 0·51 M NaCl) and the shrinkage curves were determined.

3. Worms from ‘normal’ cultures were placed in NaCN and KCN solutions and the subsequent shrinkage on immersion in a concentrated balanced salt solution was measured. From these results it is concluded that cyanide decreases the permeability of the body to water, and also that NaCN enters the body more rapidly than KCN.

4. It has been shown that the chloride solutions which produce the greatest effect on the movement of the worms produce the least shrinkage and vice versa. From this it is concluded that the substances investigated can be arranged in order of their rates of penetration approximately as follows: NaCl> CaCl2> MgCl2, KCl.

5. It is suggested that the results obtained are more easily explained on the assumption that the rates of penetration of the substances used are controlled by the activities of living protoplasm than by the properties of non-living cuticle.

Females of Littorina obesa, L. scabra and L. littorea have been shown by other workers to grow more rapidly than the males so that they predominate in the larger size groups. They are significantly more numerous than the males among the larger specimens of L. neritoides on the Plymouth Breakwater.

More male than female snails are infected by a larval trematode, Metacercaria A, when it occurs alone, and the percentage infection falls when the proportion of males falls. A second larval trematode, Cercaria B, infects more female snails than males. Infections with this species alone remain consistently low, but where it occurs in the same snails as Metacercaria A the percentage infection rises rapidly, that is, in the larger size groups of the snails where the females predominate. Females infected by Cercaria B appear then to be attractive to the metacercariae.

Evidence is given to show that it is extremely unlikely that these large female snails were originally males in which sex reversal has occurred.

This different intensity of infection of the sexes of L. neritoides is considered to be primarily responsible for the shapes of the curves when infection is plotted against size, and it does not appear likely that primary infections with larval trematodes cause acceleration of the growth rate in this species.

It is thought that ecological factors on the breakwater are likely to be the chief causes of the large size attained there by L. neritoides.

1. Three new species of dermanyssid mites of the subfamily Entonyssinae are described. These are: Entonyssus heterodontos n.sp. from Heterodon contortrix contortrix, Ophiopneumicola elaphes n.sp. from Elaphe obsolete, obsoleta, Ophiopneumicola natricis n.sp. from Natrix sipedon pictiventris.

2. Keys for the identification of male and female mites of the Entonyssinae are given.

3. 141 snakes, representing thirty-five species, were examined for lung mites. Thirteen individuals, representing eight species, were found to be infested.

4. Two species incertae sedis, one from Pituophis sayi, the other from Coluber constrictor flaviventris, are discussed.

5. Problems of classification and distribution of this group of parasites are discussed.

The use of an electrically driven Sharples super-centrifuge for isolating viruses is described. The theory of sedimentation in such centrifuges is discussed and curves of the theoretical minimum sedimentation rates are given. The probability that convectionless sedimentation cannot take place in high-speed preparative centrifuges is discussed in relation to the theory of ‘differential centrifugation’.

1. This memoir amplifies my accounts of Endolimax nana published in 1919 and 1933. The complete life-history, as observable in cultures, is now described—special attention being devoted to the nuclear structure at all stages.

2. Additional information is also given about methods of cultivation, viability of the cysts in vitro, the ‘nucleal reaction’, natural parasites (Sphaerita, etc.), and other details.

3. The life-history has been found to comprise trophic, precystic, cystic, and metacystic stages, comparable with those described in Entamoeba histolytica (1928) and E. coli (1938).

4. The trophic amoeba is redescribed, with special reference to the polymorphism of its karyosome.

5. Division of the trophic amoeba (by binary fission) has been studied, and the mitosis of its nucleus is now first described in detail. It is characterized by the formation of an intranuclear spindle, with well-developed centrioles and centrodesmus. The granular chromosomes are 10 in number, and arranged in a ring on the equatorial plate.

6. Precystic amoebae are smaller than trophic forms —the reduction in size being effected during the last two divisions before encystation.

7. The cyst is formed by a precystic amoeba in the usual way. Inside the cyst, the nucleus undergoes two successive mitotic divisions similar to those seen in trophic forms. The ripe cyst is therefore 4-micleate, though supernucleate specimens—which are viable— occur occasionally. Glycogen is normally present in young (1- and 2-nucleate) cysts, but not in those which are mature.

8. The process of excystation is described for the first time, and closely resembles that seen in E. histolytica. The entire protoplasmic contents emerge as a single 4-nucleate amoeba through a minute pore in the cyst wall.

9. Metacystic development—not previously studied —consists in simple division, by successive cytoplasmic bipartitions without division of the nuclei, into 4 uninucleate amoebulae. These grow into trophic amoebae once more.

10. The whole life-history is thus asexual, with no gametes, conjugation, or autogamy, at any stage.

During the examination of over 8000 specimens of Ornithodorus moubata, two cases of partial twinning (one male, one female) of the posterior region were noticed, and also a case of suppression of the postanal region in a male. All the freaks were viable, and the partial twins were normally fertile.

Since writing our recent review (Markham, Smith & Lea, 1942) on the sizes of viruses and the methods employed in their estimation, another virus has been added to the list of those concerning which we have concordant information by so many different methods that conclusions as to the size and shape and degree of hydration can be drawn with some confidence. This is the Shope rabbit papilloma virus, electron micrographs of which have been published by Sharp, Taylor, Beard & Beard (1942), and for which data on diffusion, sedimentation, density and viscosity have been published by Neurath, Cooper, Sharp, Taylor, Beard & Beard (1941). These data may be worked up by the formulae given in our review, and this note will serve to illustrate the convenience of our formulae for such purposes.

The following is a description of a new species of Grillotia from the intestine of Hexanchus grisens (Gmelin) caught on the Porcupine Bank in July 1939 (Rees & Llewellyn, 1941). Unfortunately, only two specimens were obtained, but, as it is unlikely that any more will be available for some time to come, it was thought advisable that the species should be put on record. The scolex includes some distinctive characters, but the strobila in both worms was immature, so that no description of the arrangement of the genitalia can be given beyond the position of the genital pore and the approximate number of testes.

A virus disease of Atropa belladonna caused by a new virus is described. The virus is sap-transmissible to tobacco and other solanaceous plants and gives good local lesions on Nicotiana glutinosa and Phaseolus vulgaris. It occurs in fairly high concentration in the plant, it withstands ageing in extracted sap for 6–11 days, and is inactivated at a temperature between 75 and 80° C.

The larval stages of the celery fly, Acidia heraclei, have been described, and it is shown that this larva agrees with other biontophagous dipterous larvae in having the pharynx devoid of ventral ridges. The transparency of the larvae permits the internal anatomy to be seen clearly in the living larva, and by this means the structure of the perispiracular glands is clearly revealed.

The braconid Adelura apii occurs as a parasite of Acidia heraclei larvae, and its first. stage larva is described in detail. This larva is densely hairy, has a long, curved, hairy, tail-like appendage and, by the more rapid growth of the ventral surface, it develops a dorsal curvature which obscures the true orientation so that the true dorsal surface appears externally to be ventral. In these respects the first stage larva of Adelura apii resembles that of A. gahani described by de la Baume-Pluvinel. The later larval stages of A. apii, of which there are at least two, are naked, lack the tail-like appendage and do not differ from the normal type of parasitic hymenopterous larvae.

A yeast-like fungus occurs as a parasite in the blood of Acidia heraclei larvae. It is always found associated with existing or abortive infection of the larvae with Adelura apii. Dense mycelial masses sometimes occur in the gut of A. apii pupae and are probably derived from the yeast cells parasitic in the host larvae. It is suggested that this is a unique case of a fungus parasitic in a host larva (Acidia heraclei) undergoing part of its development in a parasitic braconid (Adelura apii), adult females of which transmit the fungus to the host larva during oviposition.

The larva of Phaonia palpata closely resembles that of P. variegata in the structure of the buccopharyngeal armature and of the posterior spiracles. The absence of sharp teeth on the anterior ribbons and the presence of a blunt knob on the ventral edge of the oral bars distinguish the larva of P. palpata from larvae of other species of Phaonia.

The present findings apply to a particular area, the four northern counties of England, and must be viewed within the limits of the data presented.

Only one tick, Ixodes ricinus L., the so-called sheep tick, infests sheep and cattle in northern England. I. canisuga Johnston, alone or with I. ricinus, has been found on sheep dogs and foxes.

The distribution of the sheep tick in this region is markedly discontinuous, the total infested areas including only about one-fifth of the hilly country, to which the tick is almost exclusively confined.

In north-west Northumberland, tick distribution shows a significant degree of correlation with certain factors inherent in or influenced by the surface geology. Broadly speaking, where surface geology lends itself to relatively good natural drainage and soil, the grazing is relatively good and ticks are absent; and where surface geology results in relatively poor natural drainage and/or soil, the grazing is relatively poor (‘rough’) and ticks are present.

No consistent correlations between soil characteristics—i.e. pH, available phosphates and potash, soil textures, mechanical analysis and soil depth—and tick distribution have been found. Nor is there a consistent correlation- between quality of natural drainage and tick distribution. The interaction of soil and natural drainage factors, however, profoundly influences the character of the vegetation layer.

In the four northern counties, the same plant dominants occur on tick-infested and tick-free hill lands. Where grazing is rough ticks are usually present irrespective of whether the dominant plant is one of the rough grasses (Nardus, Molinia, Agrostis, Aira), bracken or heather; where grazing is relatively good (i.e. not rough), ticks are invariably absent.

Observations on a smaller scale show that the thicker, i.e. rougher, the vegetation layer, the denser the tick population and also the thicker the vegetation layer, the thicker the basal mat. On five plots it has been shown that there is a consistent positive correlation between mat thickness and tick population density: the thicker the mat,’ the denser the tick population irrespective of whether bracken or grass is the dominant. Thus the chief controlling factor in tick distribution is the physical character of the vegetation layer.

1. Scabies is usually transmitted by intimate personal contact.

2. The young, newly fertilized adult female Sarcoptes is the stage usually responsible for transmission.

3. Patients with a high parasite rate (over 100 adult female mites) are much more likely to spread scabies than those with few parasites.

4. The distribution of the parasites in clinical scabies gives no clue to the original sites of infection.

5. When a volunteer is infected for the first time he gives no reaction for about a month. During this period he may be quite unaware that the parasites are burrowing in his cuticle.

6. After a month the patient becomes sensitized, itching and other symptoms develop.

7. In a first infection the mites increase in numbers far less rapidly than is theoretically possible. A parasite rate of about 25 may be reached in 50 days and of up to 500 in 100 days; after this the number of mites decreases rapidly.

8. The second time an individual has scabies he itches at the sites of infection within 24 hr. His mite population seldom rises to a fraction of the height reached in his first infection.

9. Reinfection of cured cases is much more difficult than infection for the first time.

10. Sarcoptes causes antibody function in man. This causes a partial immunity.

11. The mechanism of immunity is due to three reactions: (a) scratching by the host which removes the parasites mechanically; (b) oedema renders the cuticle unsuitable for colonization and causes the mites to vacate their burrows; (c) scratching produces sepsis which is fatal to Sarcoptes.

12. The partial immunity obtained may account for fluctuations in the incidence of the disease.

1. The anatomy of three digenetic trematodes from Conger conger (Linn.), Skrjabiniella aculeatus (Odhner), Lecithochirium rufoviride (Rud.) and Sterrhurus fusiformis (Luhe) has been described. The technique employed is given, and in each case the history of the species has been traced.

2. The discussion on the nomenclature of Skrjabiniella aculeatus explains why this generic name used by Issaitschikow (1928) has been adopted in this work in place of Prosorhynchus, and a key to the genera Prosorhynchus s.str. and Skrjabiniella has been suggested. A table showing the proposed division of Odhner's genus Prosorhynchus is included.

3. In the discussion on the hemiurid worms it is pointed out that there is no sound basis for the separation of the genera Lecithochirium and Sterrhurus as they stand.