1. Progressive anaemia was observed in 30 White Leghorn hens obtained from a poultry farm in England, where the ailment became noticeable through the yellowish-paleness of the combs and gills of the diseased hens and the heavy mortality following on the appearance of these symptoms.

Only hens of one stock were affected, other breeds on the same farm did not develop the same or a similar condition.

2. The anaemia was characterised by a lasting diminution in the normal number of erythrocytes, a Hb index less than 1, the preponderance of immature and deformed erythrocytes and the presence of marrow-cells of the erythrocyte series in the circulating blood. The leucocytes were normal or slightly below normal in numbers; the monocytes were diminished.

3. The essential pathological lesion is an intravascular proliferation in the marrow of the stem cell of erythrocytes, which results in the blood-stream being overrun with erythroblasts and immature erythrocytes; these are rapidly destroyed in the spleen and liver, whilst the issue of normal erythrocytes in the marrow is hindered. The myeloblastic elements do not proliferate actively. These lesions explain the pathogenesis of the anaemia.

4. This intensified activity of the bone-marrow, the resulting congestion and increased localised pressure, induce the production of osteoid tissue; the femur and other bones of the fowls thicken, so that the medullary canal is nearly obliterated.

5. Attempts to detect microbes in the blood or isolate bacteria from the organs of anaemic hens failed. The spontaneously diseased hens all harbour a minute cestode, Davainea proglottina, in the duodenum, where the helminth causes round-celled infiltration, petechiae and thickening of the intestinal peritoneum.

6. In Davainea-free fowls of the same and other breeds, the injection of blood and cellular emulsions of liver and spleen from erythromyelotic fowls caused a condition of hypercythaemia which lasted several months. This was related to congestion and hyperplasia of the red-blood-marrow and accompanied by considerable enlargement of the liver and spleen.

7. Typical erythromyelosis was reproduced in one hen of the same stock from the same farm, by the intravenous inoculation of blood and tissue from spontaneously diseased fowls. In other hens only a transient type of anaemia was obtained, corresponding to the experience of other observers, more particularly Bedson and Knight (1924).

The experimental results agree with the view that a proliferative micro-plasm is the specific cause of this condition.

8. It is suggested that the development of this outbreak is induced by the massive infestation of the duodenum with Davainea proglottina. This irritative cestode produces a receptive condition in the bone-marrow of the fowl, which allows the microplasm to unfold its pathogenic properties. The duodenal parasite therefore plays the part of a preparatory cause. The association of cestode and microplasm affords an example of a “compound” disease.

9. The microplasm is specific and multiplying solely in certain definite blood-marrow cells of Gallus domesticus. This proliferative action can be compared to that of the microbes of epitheliosis contagiosa and Rous fowl-sarcoma; the resulting cell-reaction is then similar to tumour formation in these and other tissues of the fowl.

10. Since this haemopathy in fowls is characterised by specific pathological features in the erythrocyte-producing cells of the marrow, the name erythromyelosis is suggested, to mark clearly the position of the principal cellular lesion.

11. This disease (erythromyelosis) has been distinguished from other ailments of fowls, in the course of which anaemia may also occur, e.g. avian tuberculosis with involvement of the marrow. The leucocythaemic type is differentiated by diagnosis of the predominant type of cell found in active multiplication in the blood and the position of the cell-proliferation in the marrow.

12. Bone-marrow tumours and neoplasms of the lymphatic system occur in fowls, without causing progressive alterations in the cellular contents of the blood. The perivascular aggregations of cells in different organs may also hypertrophy, without any cytological changes being noticeable in the blood, except diminution of the numbers of erythrocytes. Such lesions are therefore distinguishable from different forms of leucocythaemia, where a persistent and progressive increase of genetically related cells is noticeable in the bloodstream and is concurrent with certain diffuse lesions of the marrow.

13. The haemoblastic diseases of fowls, such as erythromyelosis, leueo-cythaemia, lymphocythaemia, differ from tumours of the blood-producing tissues, since the former are the result of a pathological disturbance of the mechanism of haemocytopoiesis, whilst the latter are the localised proliferations of cellular elements, which then may spread by a process identical to neoplastic metastasis. There is a distinction in mode and degree.

14. The many resemblances between erythromyelosis and certain blood diseases in man and animals may indicate that their pathogenesis. though not identical, is comparable. A similar analogy may be applicable to fowl-leuco-cythaemia and lymphocythaemia.

1. The relation of host-parasite specificity to age resistance.

Conclusive demonstration of a substantial resistance developing concomitantly with the ageing of the host has been made with reference to four helminths, namely: Ancylostoma duodenale and A. caninum in the dog and Ascaridia lineata and Syngamus trachea in the chicken. A. duodenale in the dog and S. trachea in the chicken are manifestly in abnormal hosts. In contrast with this, it is to be noted that the normal hosts of these parasites, respectively man and the turkey, exhibit no appreciable age resistance. With regard to the remaining two cases, those of Ancylostoma caninum and Ascaridia lineata, the association of age resistance and a specific host-parasite mal-adjustment is not nearly so clear. In nature, both parasites enjoy a polyxenous distribution, neither having acquired the need for strictly specific host conditions for development. As a result of recent researches with A. caninum it has been brought out that the species is comprised of strains better adapted to one species of host than to another, and it has been demonstrated that a higher degree of age resistance is exhibited in the host parasitised with a foreign strain. Although no information on the matter is available, it is quite possible that age resistance will be found to be less markedly expressed in other species or races of suitable hosts, when the bionomics of both Ancylostoma caninum and Ascaridia lineata are further investigated.

1. The life-history of Phaenoserphus viator is described.

Four larval instars are found, endoparasitic in the larvae of Pterostichus niger. At thee nd of the last larval instar the parasites, which may number as many as 45 in a single host, emerge, and while still attached, pupate without spinning a cocoon.

Adults may appear in August or September.

The effect of the parasite in inhibiting metamorphosis of the host is discussed.

2. The first observed larva is atracheate and incompletely segmented at first and is of the polypod type bearing paired prolegs on the body segments.

Subsequent instars are apodate.

The tracheal system develops progressively in the several instars, but only becomes functional in the final stage.

3. The anatomy of the larva is briefly described with the exception of the musculature.

Tracheal development is described. Gas only appears in the tracheae after the development of the tracheole cells puts the tracheae into communication with the body wall and other organs.

In the circulatory system an important accessory organ is the neural sinus, formed by the enclosure of the ventral nerve cord beneath a connective tissue curtain.

The imaginal discs of the hypodermis are briefly described, these being clearly defined in the head, thorax, and posterior abdominal segments.

The nervous system consists of a brain, suboesophageal ganglion and 11 ventral ganglia, the most posterior being tripartite. This system is connected with the sympathetic, by nerves passing from the cerebral commissures to a frontal ganglion which lies above the oesophagus and behind the labrum.

A main feature of the data here presented is the number of new records. For the sake of brevity these are tabulated below, under their respective headings.

Another feature is the wide geographical distribution of a large percentage of the parasites herein recorded, particularly of such forms as Zoogonoides viviparus (Olsson), Derogenes varicus (Mueller) and Hemiurus communis Odhn. The former has been recorded for St Andrews, Millport, Aberdeen, Plymouth, Northumberland, Liverpool, Galway, and also for foreign seas. Derogenes varicus has been recorded for St Andrews, Millport, Plymouth, Aberdeen, Northumberland, Galway, and for foreign seas. Hemiurus communis has been recorded for St Andrews, Millport, Plymouth, Northumberland, Liverpool, Aberdeen, Galway, and for foreign seas.

This suggests that the intermediate host of the larval stages of these parasites must be some common marine form, in all probability an invertebrate, which itself enjoys a very wide geographical distribution.

A further feature is the tendency of certain parasites to infect a variety of fish, the more notorious being Derogenes varicus (Mueller) and Hemiurus communis Odhn. Of the twenty-six species of marine fishes examined at Galway, eleven (42 per cent.) were found to harbour Derogenes various. The infected fishes were the bib (G. luscus), cod (G. morrhua), pollack (G. pollachius), dab (Pleuronectes limanda), plaice (P. platessa), tub (Trigla hirundo), grey gurnard (T. gurnardus), brill (Rhombus laevis), hake (Merluccius vulgaris), common sole (Solea vulgaris), common sea bream (Sparus centrodontus).

Hemiurus communis was found parasitising eight species of fish, i.e. 31 per cent, of the total number of species examined. The hosts affected were the bib (G. luscus), whiting (G. merlangus), cod (G. morrhua), pollack (G. pollachius), flounder (P. flesus), tub (T. hirundo), plaice (P. platessa), and the common sea bream (S. centrodontus).

At the moment it is a little premature to prophesy to what extent the discovery of encysted specimens of Prosorhynchus crucibulum (Rud.) in the gill tissues of the cod (Gadus morrhua) will assist in elucidating the life-history of this parasite. Mature specimens of Prosorhynchus crucibulum have previously been recorded as occurring in the alimentary canal of the conger eel (Conger niger). The writer discovered partly digested specimens of small cod to form a considerable bulk of the stomach contents of the conger eel.

The species described in this paper were contained in a collection of parasitic worms made in Java by Dr. E. Jacobson, and sent to Prof. G. H. F. Nuttall, F.R.S., by whom the material was kindly forwarded to the writer for determination.

1. A study has been made of the effect of acriflavine upon Bodo caudatus. The drug has the property of producing a percentage of modified Bodos without parabasal bodies but no permanently aparabasal strains have been produced.

2. A technique was devised whereby the resistance, as judged by two different types of survival experiment, could be correlated with the percentage of modified Bodos produced when the strain is put to grow in an ascending series of concentrations of acriflavine incorporated in the culture medium.

3. The peak of the count of altered Bodos in relation to the concentration in which it occurs is found to be the index of the sensitiveness of the strain at that date. The maximum reaction as gauged by the numbers of modified Bodos produced in an untreated strain of average sensitiveness is about 70 to 80 per cent., and this occurs in so low a concentration as 1/1,000,000. 1/5,000,000 gives a count below the maximum and 1/50,000,000 produces only 1 to 4 per cent. according to the sensitiveness of the strain.

4. The mass untreated strain was originally derived from a single Bodo isolated in the autumn of 1926. This strain in 1927–28 was used as the mass untreated strain in the experiments. Its resistance was found to fluctuate from below a capacity to evolve with great difficulty in 1/50,000 to a somewhat feeble development in 1/10,000 acriflavine incorporated plates. The mass untreated strain was never able to evolve in plates containing 1/5000 acriflavine at any time.

5. Strains grown from single isolations from the untreated mass culture showed different degrees of natural resistance. The most resistant clones could develop in 1/5000 acriflavine incorporated plates, but not in 1/2000. The great importance of this natural range of resistance in estimating an acquired drug fastness is emphasized. Strains which had been made resistant could be brought to live continuously in 1/1500 acriflavine incorporated plates, but no evolution was obtained in 1/1000.

6. Evidence that drug fastness in Bodo caudatus is due to the interaction of selective inheritance and the actual modification of the quality of the Bodo by evolution in the drug is given. The modification is not apparently a mutation, it is a heritable piling up of changes in a particular direction.

7. A high resistance once acquired is retained through prolonged cultivation upon drug-free media. A gradual loss occurs, partly by a dilution through multiplication of the character impressed and partly by the survival of variants of less resistance to acriflavine, but of perfect viability in other circumstances and the competition of these within the strain. The loss of resistance is greatly accelerated in single cell cultures (clones) isolated from the resistant strains, but up to the present no treated strain has entirely lost the effect of the original exposures to the drug. The longest time elapsing between the creating of a partially resistant strain and its test for resistance above that of the untreated culture is one year.

8. The bearing of the data obtained in Bodo caudatus upon the condition found in trypanosomiasis and upon certain aspects of chemotherapy in this group is discussed.

9. Bodo caudatus being an organism without conjugation and therefore without bi-parental inheritance and consequently lacking the reorganising effect that such a periodic closing of the cycle produces, affords an example of a labile organism capable of being progressively altered within certain limits under the influence of the environment.

The structure of the head and mouth parts of the Streblidae has been very briefly described by Speiser (1900) and subsequently by Muir (1912) in the genera Ascodipteron and Nycteribosca. The description given by the latter author is, however, still incomplete. Having, therefore, collected the necessary material I have re-investigated their structure and compared it with that of the Hippoboscidae and the Nycteribiidae, already described by me elsewhere (1926 and 1928).

1. The enzymic activity was studied in the following Dermatophyte fungi: Sabouraudites radiolatus; S. lanosus; S. audouini; Trichophyton tonsurans; Grubyella schoenleinii. Both the normal and pleomorphic forms of S. radiolatus were studied comparatively.

2. An active proteolytic enzyme is present in all the species. This enzyme is active in an alkaline medium and can hydrolyse intact proteins (casein) with the production of free amino-acids (tryptophane), and is very similar to trypsin in its behaviour.

3. Pepsin is not present in any of these fungi.

4. The amount of the proteolytic enzyme present varies in the different species, and it is particularly abundant in S. radiolatus.

5. A keratolytic enzyme was not found in any of these fungi.

6. A lipolytic enzyme, lipase, which readily splits tributyrin into fatty acids, is present in all the species. It is about equally strong in all of them.

7. Urease is present in all, with the exception of T. tonsurans.

8. None of them contains invertase, inulase, lactase or zymase.

9. Maltase and diastase are present in all. They are strongest in S. lanosus and T. tonsurans and are weakest in S. radiolatus.

10. The species with most proteolytic activity have least carbohydrases, and conversely.

11. Amygdalase is present in all the species.

12. The normal form of S. radiolatus has greater proteolytic activity than the pleomorphic form. The pleomorphic form has strong urease and amygdalase, both of which are very weak in the normal form. Otherwise the enzymic activity of the two forms is similar.

Jameson (1926) has described from the caeca of cattle a ciliate belonging to the family Isotrichidae to which he has given the name Buxtonella sulcata. The most prominent character of this ciliate is a dorsal ridge running in a wide sweeping curve from one end of the body to the other with a groove running down the middle. Other characters of importance are a peculiar indentation near the mouth and the not uncommon occurrence of the macronucleus in two separate rounded portions. Roundish oval cysts of this ciliate, 80 to 100 microns in length by 60 to 80 microns in width, were also found by him.

Five tame monkeys (3 Macacus sinicus and 2 M. rhesus) have been treated with emetine bismuthous iodide per os, in order to study the effects of the alkaloid upon their intestinal amoebae (and other protozoa).

These monkeys were originally infected with Entamoeba histolytica (large and small strains), Entamoeba coli, Endolimax nana, Enteromonas (= Tricercomonas), and Giardia. Treatment with emetine ultimately eradicated the E. histolytica infections from four out of five animals, but did not remove any of their other intestinal protozoa.

It has been found necessary to administer 60 mg. of emetine bismuthous iodide daily for about a week to a macaque weighing about 5 kg. in order to eradicate an infection with E. histolytica. Such dosage was toxic to four of the five monkeys used.

The general conclusion drawn is that emetine affects the various intestinal protozoa of M. sinicus and M. rhesus exactly as it does the comparable species in man; and it is suggested that macaques can therefore be utilized—if similar methods be employed—in place of men in future chemotherapeutic experiments directed towards the discovery of remedies for human amoebic dysentery.

1. Four species had been described to date as belonging to the genus Catoptroides: C. spatula and C. spatulaeforme from African catfish and C. macrocotyle and C. angulatus from European fish.

2. C. lacustri, a new species described in this paper, was taken from the great fork-tailed catfish, Ameiurus lacustris, from the St Croix River, Minnesota.

3. To this list must be added C. staffordi of the American catfish, Ameiurus nebulosus and A. melas, which was described by Pearse in 1924 and placed in the genus Phyllodistomum.

4. C. angulatus is shown not to be a member of this genus, but rather as belonging to the genus Phyllodistomum in which von Linstow first described it.

5. All of these species are briefly reviewed and compared in this paper.

There can be no doubt that reasoning by analogy contributes enormously to the progress of Science by suggesting the hypotheses which form the basis of experimental investigation. But although it is useful, it is also dangerous and it is not infrequently the source of plausible but inaccurate and misleading catchwords.

In response to my request for specimens of blood from Lepidosiren paradoxa, Dr G. S. Carter and Mr L. C. Beadle very kindly made a large number of dried films from 34 fish caught between the dates Sept. 25th, 1926, and May 24th, 1927. These fish were caught in the same locality in the Gran Chaco from which came the infected specimen of my former note (Jepps, 1927), on the parasite which I called Haemogregarina lepidosirenis.

The Helminths herein reported are of importance because of their economic and taxonomic relations. To point this out, it is only necessary to mention Haemonchus, whose relation to the Bovidae and Ovidae is equivalent to those of Necator and Ancylostoma to the human host.

Some are well-known roundworms having a world-wide distribution as parasites of animals, and are listed only on account of locality and museum interest; others, especially certain rare forms from uncommon hosts, are of greater interest and are discussed more fully. Certain details, at one time thought not.to be necessary and hence neglected are added because to-day they are indispensable for specific designation.

Because of the abundance of material, it has been possible to supplement accounts given by other authors and to correct some errors due, no doubt, to poor or too few specimens. Several changes in systematic position of known forms and confirmation of others are made.

A new name (D. histrix) is proposed for Dirofilaria subcutanea (Linstow, 1899) Boulenger, 1920. Eustrongylides larvae, of Ciurea, J. 1924, are included under the pre-adult stage of a new species (Eustrongylides wenrichi) because both are alike and their characters fit no other known species. New information is added about Trypanoxyuris trypanuris Vevers, 1923, and Cyrnea coloni Cram, 1927, amending their descriptions.

Descriptions and illustrations of seven new species in as many genera are given. They are Acuaria (Dispharynx) resticula from a groove-billed ani, Ascaridia petrensa from a partridge, Dirofilaria spinosa from a porcupine, Physaloptera multiuteri from a monkey, Subulura pennula from a quail, Spironoura procera from a terrapin, and the above-mentioned pre-adult Eustrongylides wenrichi from a stream pike, brook-trout, calico bass, sunfish, and a frog.

In all there are 162 determinations in 38 genera and 56 species, including new ones, from 150 hosts involving 117 different host species.

Superparasitism and significant cases of parasitism are pointed out because they are of interest to one concerned with incidence and degree of infestation. Numerous records of new host-parasite relations and new localities will be of interest to students of distribution.

From the small intestine of a lynx, Lynx canadensis, killed in the vicinity of Minneapolis, Minnesota, four strobilae and two fragments of an undescribed taenioid cestode were recovered. The largest of these tapeworms, which is the only one containing segments in all stages of development, measures 31 cm. in length and contains 253 proglottids; the other three strobilae measure 8, 26 and 30 mm. in length, respectively. The two fragments, one consisting of three and the other of eight ripe proglottids, apparently are segments from the largest one of these four strobilae.

The anatomy, histology and digestive enzymes of the mid-intestine of the tsetse-fly have been investigated, and an attempt has been made to determine the functions of the various parts and to observe the changes to which they are subject during the digestion of blood.

Histologically the mid-gut of Glossina consists of three regions:

(i) An anterior segment of small, pale-staining, irregularly columnar cells, which comprises about half the total length of the mid-gut. The zone of giantcells containing bacteroids, which is very limited in extent, lies at about the middle of this region.

(ii) A middle segment of large, deeply staining cells, heaped together in the resting state, which is separated abruptly from the anterior segment.

(iii) A posterior segment, arising by gradual transition from the middle segment, composed of regular columnar cells.

After a meal the blood is concentrated by the removal of fluid in the anterior segment but it shows no other change in this region. The giant-cells are greatly flattened but they do not regularly discharge the bacteroids which they contain and there is no evidence that these organisms play any part in the digestion of blood. Their possible function has been discussed.

During digestion the cells in the middle segment contain globules of secretion, and vacuolated buds of cytoplasm are set free and disintegrate in the lumen. The blood shows an abrupt change on reaching this region; it turns black where it is in contact with the epithelium and amorphous masses of altered blood pigment are deposited.

In the posterior segment, the epithelial cells become greatly vacuolated later in digestion and are probably concerned chiefly in absorption.

The distribution of digestive enzymes agrees with these histological observations. The salivary glands and proventriculus contain no digestive enzymes, and the anterior and posterior segments of the mid-gut also are practically inactive. But the middle segment produces a very active tryptase which agrees in its pH-activity curve and other properties with the tryptase of the cockroach. A peptidase also is present but, except for a very weak amylase, enzymes acting upon carbohydrates are absent. The contents of the mid-gut are always slightly acid (about pH 6·5) and the tryptase present is well adapted to work at this reaction.

These findings have been contrasted with those in a non-blood-sucking muscid (Calliphora). Here the salivary glands secrete an active amylase and the mid-gut is rich in amylase, invertase and maltase, whereas the proteolytic enzymes are extremely weak.

Some observations have been made upon the tracheal supply to the walls of the gut. The epithelial cells of the middle segment have been shown to contain a very rich supply of intracellular tracheoles. These are usually difficult to make out in the resting cells but after a large meal the surface of the cells is ruptured and blood pigment enters the tracheoles and may extend to the sub-epithelial tracheoles and tracheae or even to quite large tracheal trunks. As the epithelial cells are flattened by the pressure of the meal, this pigment is set free in the lumen in the form of dark rods of haematin, which often bear a superficial resemblance to bacteria. The pigment in the deeper tubes appears to be slowly absorbed later. Intracellular tracheoles similar to these are present also in the mid-gut of Calliphora.

The proventriculus in Glossina is a complex and has always been a puzzling structure. It has been shown that it acts as a sphincter between the fore-gut and mid-gut and that it is responsible for the production of the peritrophic membrane. This membrane, which is composed of chitin but contains a small quantity of protein, is secreted in the form of a fluid by the ring of large epithelial cells at the base of the proventriculus. The fluid is pressed and condensed to form a uniform membrane by being drawn through the cleft between the wall of the proventriculus and the funnel-shaped invagination of the fore-gut.

The function of the peritrophic membrane has been discussed and it has been shown that it is freely permeable to digestive enzymes and to haemoglobin.

For the opportunity to examine the material on which the following descriptions are based I am indebted to the courtesy of Dr P. A. Buxton and Miss E. Sikes of the London School of Tropical Medicine, where the life-history of certain fleas is being studied. A detailed examination of the parasite showed it to be referable to the Pirenine tribe of the Miscogasteridae—a family of Chalcidoid wasps. The genus and species appeared to be new. The fact, however, that the parasite had been bred from a species of flea known to have been recently introduced into Britain suggested the advisability of comparison with American representatives of the Pirenine group. This has now been done by my friend Mr A. B. Gahan of the Bureau of Entomology, Washington, D.C., to whom my hearty thanks are due. As the result we are agreed that a new genus is required. Bairamlia n.g. has obvious affinities with Pirene Hal., but differs in antennal, neurational and propodeal characters. Ecrizotes Forst. (fide A. B. Gahan) may also be a nearly related genus. genus. As regards the species, I am satisfied that it is very different from anything described by Walker of which material is still extant in the British Museum. Mr Gahan, however, tells me that Pirene marylandensis Gir. (Canad. Ent. 48, p. 116, 1916) is a congeneric though distinct species.

In 1926 Bequaert wrote, “In the light of the theory of evolution, the various cases in which hemipterous insects, that are normally predaceous or even phytophagous, occasionally become blood-suckers are of considerable interest. They show that haematophagous habits may be readily and rather suddenly acquired by insects that have developed suitable piercing and sucking mouth-parts, without previous adaptation to a blood diet.” These remarks accompanied an annotated list of the species of Hemiptera known to bite man without provocation. In the list are included six species of Cimicids and eleven Reduviids (Triatoma and Rhodnius) which are apparently obligate blood-suckers of Vertebrates; and nine Reduviids, one Nabid, five Anthocorids, and two Lygaeids (Geocoris henoni Puton and G. scutellaris Puton) which are normally predaceous on other insects, whose haemolymph they suck, being thus obligate blood-suckers of Arthropoda. The case of Clerada apicicornis Sign. is obscure, though this species is probably normally predaceous on other insects. An Australian species (C. nidicola Bergr.) is an inquiline in the nests of “opossums” (phalangers).

1. Two pure strains of Entamoeba coli, differing in their accompanying bacterial flora and experimental history, but identical morphologically, have been tested with emetine hydrochloride in vitro.

2. In a buffered and wholly liquid medium, with a pH varying between 6·8 and 7·2, emetine hydrochloride was found to be toxic to E. coli in dilutions between 1 : 300,000 and 1 : 600,000, the toxicity increasing with the alkalinity of the medium.

3. It is therefore concluded that emetine is about 16 times as toxic in vitro to E. histolytica as it is to E. coli.

The Trematode herein described was obtained from the gills of Trigla hirundo Day, popularly called the Yellow Gurnard, Latchet or Tub, one of the most common species of the Gurnard family found on the west coast of Ireland.