A simple method is described for eliminating the symbionts from the body louse during the egg stage, and thus producing symbiont-free larvae. The behaviour of lice freed of their symbionts by this method is described and compared with that of lice freed of their symbionts by extirpation of the larval mycetome.

The complete accord of the results obtained by the different methods warrants the conclusion that the symbionts play an essential role in the life of the louse, so much so that without them death of the larvae results. It is, therefore, justifiable to consider this relationship true symbiosis.

1. The following strains produced no infection in any of the laboratorybred Glossina used in their examination; the total number of flies dissected is given for each strain:

T. gambiense, strain V, Uganda, isolated in 1926 … … … 548

T. gambiense, strain Adero, Uganda, isolated in Jan. 1933 … 1642

T. rhodesiense, Liverpool, isolated in Jan. 1933 …. … … 750

T. rhodesiense, Liverpool, arsenic-fast variant … … … … 1166

T. brucei, “Hamburg alt” from Berlin; isolated over 30 years ago 2452

Some of the flies used in testing each of these strains were kept at 95–97° F. during their infecting feeds.

2. T. gambiense, strain “Braun,” isolated in February, 1920, gave two “gut only” infections in 1137 flies. T. gambiense, strain “McA,” isolated in 1921, produced one very light infection, of the intestinal tract only, in 1410 flies employed. This infected fly died on the 27th day after its infecting feed.

T. brucei, strain “Hornby mild,” isolated at the end of 1930, gave three infections of the intestinal tract only in 1443 flies used. Some of the flies employed on these three strains were kept during their infecting feeds at 95–97° F., but the infected flies came from boxes kept at room temperature throughout.

It will be seen that all the strains hitherto summarised are, as far as these tests are concerned, non-transmissible by Glossina, and the majority are no longer capable of infecting even the intestine of the fly.

3. T. brucei, strain “Hornby virulent,” isolated in April, 1927, from a heifer, and found by Corson in 1931 to be readily transmissible by G. morsitans or G. pallidipes (or both), 4½ years after its first isolation (Corson, 1932). A month or so later this strain was found at Entebbe to be still feebly transmissible by G. palpalis and somewhat more readily by G. morsitans, although much less so than in Corson's experiments.

4. Strain “Br,” considered by Prof. J. G. Thomson to be a T. gambiense showing some resemblances to T. rhodesiense, when examined at Entebbe some three years after its isolation from a European in West Africa, proved to be still infective to both G. palpalis and G. morsitans through only very feebly transmissible. 4272 laboratory-bred flies were used in the examination of this strain: 74 of these developed infection of the intestine, and only one a gland infection—a G. palpalis dying on the 40th day after its infecting feed. Flagellates were numerous in the glands of this fly.

5. The behaviour of the “Hornby virulent” strain of T. brucei and of strain “Br” suggests that completion of the cycle in the fly may be delayed beyond the 25–30 days usually sufficient for East African strains, and it is possible that this delay may be a feature characteristic of strains whose transmissibility by tsetse is undergoing reduction. On the other hand, the solitary infective fly obtained with strain “Br” had a heavy gland infection which had in all probability been present at least for several days before the death of this insect.

6. A strain freshly isolated from a native who was infected on or near the northern shores of Lake Victoria failed to infect any of 1642 G. palpalis used in its examination, although a number of these flies were kept at 95–97° F. during their infecting feeds.

7. The results of the investigations described in this paper lend some support to the opinion already formed as the result of numerous experiments with the polymorphic group of trypanosomes, namely that T. brucei (and, as far as can be seen, T. rhodesiense) is less prone than T. gambiense to lose touch with Glossina.

It may be that the stability of this character in T. brucei is an expression of a more perfect adjustment to environment than is possessed by T. gambiense; the latter trypanosome, which is essentially dependent on man, having not yet attained biological equilibrium in this its principal mammalian host.

1. A fungus disease of epidemic proportions was found in the common sea herring (Clupea harengus) throughout the Gulf of Maine.

2. The fungus was also found to infect the common winter flounder (Pseudopleuronectes americanus) and the alewife (Pomobolus pseudoharengus).

3. The causative agent was found to be a species of fungus belonging to the genus Ichthyosporidium Caullery and Mesnil (1905). The specific name is tentatively accepted as hoferi Plehn and Muslow (1911).

4. The organism is believed to be a normal parasite to the herring and reaches epidemic proportions only when certain unknown factors are operative.

5. The causative organism was found in herring preserved in 1926, and it is believed that the epidemic has been increasing in severity since that time.

6. It is believed that such an epidermic, once initiated, increases in severity, reaches a peak, and subsides to a subpatent level. The peak is believed to have been reached in 1931.

7. The life history and effects of the organism in the herring and flounder are described.

8. The herring is believed to acquire the infection by the ingestion of parasites liberated from fish in the same school.

9. The flounder is believed to acquire the infection by the consumption of infected herring.

10. The alewife is beleived to acquire the infection by ingestion of the parasite during its infrequent association with the herring.

11. Infection is believed to be established by way of the alimentary canal and, once established, to spread throughout the host by way of the blood stream or the lymphatics.

12. Direct cross infection from the herring to the flounder establishes the theory that the parasites in these two hosts are one and the same organism.

13. Direct cross infection experiments from the herring to the flounder eliminate the necessity of an intermediate host.

14. There is no reason to believe that this parasite is capable of infecting warm-blooded animals.

During a survey of the helminth fauna of the domestic cat in the immediate vicinity of Foochow, Fukien Province, China, the junior author discovered paired roundworms in the vestibule of the middle ear of this host. These parasites were first found in 1932 and again in the spring and fall of 1933. There appears to be no seasonal infection. Of forty-eight animals sacrificed eleven (22·9 per cent.) were found to be infected.

The two subjects considered in this paper are of practical importance to those interested in research of the kind carried out at the Human Trypanosomiasis Research Institute, Uganda. Their discussion would seriously encumber a report on experimental work and would distract the reader's attention from the main theme. The subjects are therefore dealt with separately, since they bear on all work, past and present, carried out at the Institute.

In 1904, Bezzenberger investigated ciliates from the rectum of several amphibian hosts of Asia and described two new species of Nyctotherus, N. macropharyngeus and N. magnus. Recently Dashi Nie (1932) described two more new species, N. nankingensis and N. pyriformis, with several opalinids from Rana limnocharis Gravenhorst of Nanking. It is the purpose of this paper to describe a new species of Nyctotherus from the Chinese frog, Rana spinosa.

1. Embadomonas intestinalis has been cultivated on an inspissated horse-serum slope covered with Ringer egg-white or with inactivated horse-serum diluted 1:10 in 0·5 NaCl solution, at 17–20° C. as well as at 37° C.

2. Attempts to infect tadpoles of Bufo vulgaris, bred free from Protozoa, with E. intestinalis have failed.

3. In the division of E. intestinalis there is duplication of the basal granules and flagella with the formation of a centrodesmose between one granule of each pair. The cytostome disappears and new ones are formed when nuclear division is complete. No spindle fibres are formed but the nucleus becomes spindle-shaped and discrete chromatin granules are present.

4. Double individuals occur but they do not represent a stage in normal division. Long observation failed to reveal division of such individuals.

5. Cysts of E. intestinalis have been found in cultures at all temperatures studied. The nuclear membrane and peripheral chromatin is elongated and stains intensely, and the two basal granules are prominent. A siderophilic mass in the centre probably represents the karyosome. There is no evidence that division occurs in the cyst.

In human schistosome infections there is always the possibility that a patient may harbour a preponderance of male parasites, or that female parasites may be absent or remain undeveloped for long periods of time. This possibility is not generally recognised, in spite of the fact that the above-mentioned conditions are frequent in experimental tests. And it is evident that, if such conditions do hold for man, the mere absence of eggs from the urine or faeces is of little avail in determining the presence of an infection or in estimating the effects of treatment. Since, further, the ova are not readily detected in faeces and slight infections of the urine are demonstrable only when the very last drops of urine are collected and centrifugalised, a less uncertain and laborious method of estimation is clearly desirable. The complement-fixation test is not entirely trustworthy, though a negative result and a normal blood count would prove useful evidence of successful treatment. It is suggested in this paper that the degree of eosinophilia may afford a reliable confirmatory test.

1. Cysts of Trichomonas batrachorum have never been found in repeated examinations of faeces nor of cultures made from them from Bufo vulgaris and Rana temporaria.

2. In dilutions of cultures in rain water with large surfaces exposed to the air Trichomonas batrachorum dies in forty-eight hours; but in long columns of water and absence of oxygen they live, in some cases, for months.

3. T. batrachorum will not live at 37° C., and T. hominis, though it lives at room temperature, will not multiply.

4. Tadpoles of Rana temporaria and Bufo vulgaris and larvae of Salamandra maculosa have been reared free from Protozoa.

5. Tadpoles of all three species of Amphibia have been infected with Trichomonas by feeding them on cultures free from cysts.

6. Tadpoles of Rana temporaria can be infected with Trichomonas batrachorum isolated from Bufo vulgaris, and tadpoles of B. vulgaris with Trichomonas from Rana temporaria. It is concluded therefore that Trichomonas batrachorum in frogs and toads is one true species.

7. Trichomonas sp. isolated from Lacerta viridis will not infect tadpoles of Bufo vulgaris and Rana temporaria.

8. Cultures of Trichomonas batrachorum from Bufo vulgaris will infect larvae of Salamandra maculosa though this species of Trichomonas has not been described from this amphibian.

The insect parasites bred out of Psyllid hosts, in the course of studying their biology in Scotland, belong to four families of Hymenoptera and one of Diptera, the total number of species encountered being seven. Of these one and possibly two more of the hymenopterous species are hyperparasites. The hosts involved include four species, of which only one, Psyllia mali race peregrina, may be said to have been fairly heavily parasitised. As observed by Ferrière (1926), species of Psyllidae, in spite of their nymphs leading a comparatively sedentary life, are less susceptible to attack by parasites than are the other Homoptera. As a rule the hymenopterous parasites attack them in the nymphal stage, while the dipterous species parasites the adults as well.

Host and record. Several males and females were collected from the skin of a sailfish, Histiophorus gladius Day, caught off the south coast of Ceylon in December, 1931. Since then this form was found to occur commonly as an external parasite on the skin of many of the sailfish and swordfish found in Ceylon waters.

A single specimen of a blood fluke was obtained from the gills of an amberjack or coronado, Seriola lalandi Cuv. and Val., taken by the writer on November 30th, 1929, from the Atlantic Ocean off Miami, Florida. This fluke belongs to the family Aporocotylidae Odhner 1912, and is regarded as the type of a new genus.

Two species of Nematodes belonging to the genus Trichostrongylus, namely, T. tenuis (Mehlis 1846) Railliet and Henry 1909, and T. pergracilis (Cobbold 1873) Railliet and Henry 1909, have been described from birds, the location of both species being the caeca. A third species, described as Strongylus douglasi Cobbold 1882 emend. Gedoelst 1911, from the proventriculus of the ostrich, is considered by some authors as belonging to the genus Trichostrongylus, and by others, notably Lane (1923) and Nagaty (1932), as necessarily referred to a distinct genus, Libyostrongylus, with which latter opinion we are inclined to agree, as a result of examination of specimens of this species.

Many species of cephaline Gregarines have been previously described from hosts belonging to widely different orders of Crustacea. These parasites are referred to the families Cephaloidophoridae Kamm, Gregarinidae Labbé, Porosporidae Léger, and Didymophyidae Léger. Kamm (1922) gave a list of these parasites, instituted the new family Cephaloidophoridae, and gave a description of all the species, except those referrable to Porosporidae, as till that time it was generally believed that Porosporidae were Schizogregarines. She fully discussed the grounds for placing the genus Cephaloidophora Mawrodiadi in a family by itself, and transferred to this genus several species previously described under Gregarina or Frenzelina.

1. Of 259 cockroaches (Periplaneta americana) collected at Manhattan, Kansas, 86·3 per cent. were infested with one or two species of oxyurids, Leidynema appendiculata and Hammerschmidtiella diesingi. The highest incidence was among the immature roaches, of which 94·2 per cent. were infested; next was in the adult females with 87·5 per cent. infested; and lastly among the mature males with 79·5 per cent. parasitised. The female roaches carried the heaviest infestations and the young Periplaneta americana the lightest.

2. Uninfested cockroaches were obtained by rearing the young from oöthecae.

3. Oxyurid eggs in moist chambers remained viable for at least two months. Eggs of all stages when exposed to direct strong artificial or natural light for 15 min. failed to continue development.

4. Fertilised eggs incubated at 37° C. in dilute Locke's solution develop to the active embryonated stage in 20–36 hours; in 4–7 days they develop to the resting embryonated stage.

5. Regardless of the media utilised eggs failed to hatch in vitro.

6. Feeding experiments proved that transmission is direct. Eggs in the resting embryonated stage are infective; those in the active embryonated stage do not appear to be infective.

A detailed description of the musculature in the different regions of the alimentary canal of Calliphora erythrocephala is given, and an account of the structure and function of the crop, proventriculus, ducts of the Malpighian tubes, rectal valve and rectal papillae. It has been shown by dissections and experiments that a system of channels exists in the rectal papillae through which the body fluid probably circulates, and it is suggested that the very large cells may have functions resembling those of liver cells.

Clinical trichostrongylosis, caused by T. tenuis in the caeca, previously known in epizootic form among gallinaceous birds in Great Britain, is here reported for the first time in this country, in native domestic geese in the District of Columbia and in imported pheasants in Michigan.

In cultures made from caecal contents of infected pheasants, eggs hatched in 36–38 hours; the infective larval stage might be reached as early as the sixth day (fourth day after hatching). Moisture being present, migrating larvae, retracted within the cuticular sheath, resisted an average temperature of about −3° C. (range +3° to −20° C.) for 4 months, proving infective for a bird host at the end of that period. The chicken, turkey and guinea-fowl were successfully infected with cultures derived from pheasants; attempts to infect the duck and pigeon with cultures from pheasants, and to infect the duck with cultures from geese, were unsuccessful. Development to adults in bird hosts took place in a minimum of 7 days after infection; the size of adults varied in different birds, being greater in the chicken than in the pheasant, and still greater in the turkey. In early stages of infection diarrhoea from the caeca, with passage of mucus and blood, occurred; later all discharge from the caeca ceased. The pathological picture was that of acute typhlitis, with the trichostrongyles lying in close contact with or penetrating the mucosa. Reinfection being prevented, symptoms were of fairly short duration, and the infestation tended to die out in about 2 months.

1. Observations indicate that the female uses the third pair of legs during deposition as an aid in forcing the larva through the vaginal orifice.

2. The young imago is able to free itself from the pupal case by dragging the case across a rough surface with the forelegs.

3. The act of copulation has been observed and described, including mounting, position and duration.

4. Evidence is presented to show that the insects are positively thermotropic and thigmotropic; negatively phototropic and hydrotropic.

5. The flies react positively to the odours of oil of cloves, camphor and ox gall; negatively to oil of wintergreen and amyl alcohol, and are indifferent to blood, fresh pigeon skin, pigeon scales, feathers, ammonia, oil of thyme, oil origanum, xylol and bergamot.

6. The length of life without food is found to be in direct proportion to the energy expended in motion, ranging from 77 to 109 hours.

7. The flies refuse to take unwarmed food.

8. The insect will not penetrate a perfectly smooth membrane, or one that is rancid.

9. According to data presented. Pseudolynchia maura will not live longer than 117 hours when artificially fed.

The present paper deals with a collection of parasites from Malay, kindly sent to Prof. Keilin at the Molteno Institute by G. B. Purvis, F.R.C.V.S., to whom the writer wishes to express his appreciation of the painstaking and scientific way in which the collection was carried out. The specimens were all very carefully sorted and clearly labelled, and the majority extremely well preserved.

A flagellate from Polietes lardaria, closely allied to Herpetomonas muscarum, has been repeatedly isolated in bacteria-free culture by the use of quinanil after numerous attempts to isolate it by other methods with one exception had failed. The flagellates were exposed to 1/10,000 or 1/100,000 quinanil for 2–4 or more hours and cultivated in Locke serum agar, the medium for the first subculture containing quinanil in concentrations of 1/10,000 or 1/50,000. The proofs of the purity of the cultures were exhaustive.

We are greatly indebted to Dr St John-Brooks and the National Collection of Type Cultures for certain of the flagellates isolated by Noguchi and Tilden. One of us (F. C. H.) has also been in receipt of grants from the Medical Research Council, and he would like to take this opportunity of expressing his thanks to that body.