A consideration of the therapeutic doses generally used by South African doctors who avoid toxic effects during the treatment of schistosomiasis indicates that a permanent cure of the disease may be effected with either the potassium salt or the sodium salt of antimony tartrate within a month. A dose of 2 grains need never be exceeded with antimonium potassium tartrate in fresh solution as a maximum repeated dose. A total of 20 grains of this salt is a sufficient total dose; but the solutions of the drug should not be kept. The sodium salt of antimony tartrate was found less stable than the potassium of this compound.

Some time ago I received for identification a microscopic preparation of parasites taken, on 11 March 1929, from a flying squirrel (Sciuropterus volans L.) in the neighbourhood of Agraz, Tartar Republic. The preparation mounted in Canada balsam contained one male and two females. Later I examined a rather large collection of flying squirrels in the Division of Mammals of the Zoological Institute of the Academy of Sciences of U.S.S.R. In one jar containing a flying squirrel from Verchoijansk, Yakutia, 67° 33′ N, 133° 51′ E, I found, among the debris on the bottom, a single specimen of the same parasite.

During my stay at the Zoological Station of Wimereux, Pas de Calais, France, in August 1934, I made a special study of Protozoa parasitic in marine fishes. The examination of ten specimens of young Raia batis revealed a coccidial infection in two individuals, measuring about 25 cm. in length. In one of these the mucus in the terminal portion of the intestine contained a few unsegmented spherical oocysts, with diameters from 24 to 28μ. Sections of different portions of the intestine and of the liver failed to exhibit any stages of schizogony or gametogony, evidently owing to the fact that there was a single infection at the end-phase. However, the second skate showed very numerous unsegmented oocysts in the posterior portion of the alimentary canal (Pl. I, fig. 1). This specimen provided material for the morphological study and biological observations which follow.

In this paper the history is given of the maintenance away from man of certain strains of T. rhodesiense originally isolated from man in Tanganyika Territory.

In this, the last paper to be published from the Uganda Institute, after an account of the strain that forms its main subject, the origin of T. rhodesiense will be briefly discussed in the light of the investigations recorded in this series of papers and a few general observations will be made.

An account is given of the spontaneous occurrence in the Anglo-Egyptian Sudan of strains of the camel trypanosome, Trypanosoma evansi, devoid of kinetonuclei.

These cases, of which four are recorded, were observed in widely separated localities within the enzootic area of camel trypanosomiasis.

A critical review is given of the question of “akinetonucleate” trypanosomes in general—in strains produced experimentally and in those occurring spontaneously—with special reference to their mode of origin and their significance in the production of new races.

The prevalence of “akinetonucleate” forms in normal strains of trypanosomes has been estimated in the case of a number of species and races hitherto not examined from this point of view, all the existing data being brought together in tabular form.

While the factors causing the appearance of “akinetonucleate” individuals and strains under natural conditions could not be ascertained, irregular division of the trypanosomes is held to be mainly responsible for the elimination of the kinetonucleus and for the persistence of the aberrant condition.

1. In Entamoeba aulastomi excystation does not occur in vitro until the glycogen and chromatoids have been absorbed.

2. The product of excystation is a quadrinucleate amoeba.

3. The amoeba escapes through a minute pore in the cyst wall.

4. No evidence of sexual phenomena has been obtained during the metacystic cycle.

5. The excysted quadrinucleate amoeba undergoes a series of nuclear and cytoplasmic divisions. These divisions do not necessarily synchronize or alternate with one another, but by them 8 uninucleate amoebulae containing daughter nuclei are ultimately produced from every cyst. Amoebae containing 6, 7 or 8 nuclei may appear in the course of the metacystic development.

An account is given of a virus which is present in the roots of a number of different plants. Plants which have been shown, so far, to contain the infective principle in the roots are several members of the Solanaceae, tomatoes, tobacco, etc.; of the Primulaceae, Polyanthus sp. and Primula obconica; of the Geraniaceae, zonal Pelargonium; and of the Compositae, the aster. Such plants show no indication of infection with the exception of Nicotiana tabacum and N. glutinosa, which may develop natural disease symptoms. These symptoms are usually confined to the two lowermost leaves and develop most frequently under conditions of low temperature and low light intensity. The virus never becomes completely systemic in any host plant and is generally restricted to the inoculated leaves. Experiments are described which show the virus to be present in the roots of tobacco plants which had given a negative virus reaction a few weeks earlier. The virus is found in the roots of tobacco plants arising from seed which has been heated to a temperature of 75° C., the thermal death-point of the virus in expressed sap being 72° C. All attempts to demonstrate the presence of the virus in the seed have proved negative.

Although no systematic study has been made, the range of plants susceptible to local infection in the leaves, by artificial inoculation, seems wide. Tests have shown that about 25 species of plants belonging to 10 families respond to inoculation with the virus.

Three possible explanations of the origin and spread of the infection are discussed.

The results are described of further studies on a virus found in the roots of certain normal-looking plants. It is shown that the virus is a contamination arriving from outside sources. The virus has been detected in the sludge at the bottom of the water tanks, and the experimental evidence shows that it is water-borne to the soil whence it reaches the roots of the plants. Experiments to test the possibility that the virus is also air-borne have so far proved negative.

The virus is exceedingly resistant, it can be completely desiccated and remains infective in the dry state for many weeks. It is also unaffected by alcohol and is still infective after being stored in absolute alcohol for 6 months.

The virus is thought to be a transitional stage between a pathogen and a non-pathogen.

1. Sheep myiasis was investigated in certain districts in Ayrshire, Arran and Argyllshire.

2. Larvae from cases of myiasis were collected and bred out in flyproof apparatus.

3. The fly season was found to last approximately from May till September, reaching its height in July and August.

4. The western districts were found to be the most heavily affected.

5. The flies were found to be partial to low-lying, sheltered ground, especially where much bracken was present.

6. The methods of carcass burial were found to be primitive and inadequate. In most of the farms dipping was carried out without sufficient attention to cleanliness and adequate time of immersion.

7. The hibernation of various species of blow-fly was studied. They were found to pass the winter as prepupae, pupation never occurring normally till April or May.

8. Several species of carrion-feeding blow-fly besides Lucilia sericata were found to be causing secondary myiasis, occasionally and in small numbers, in certain districts, mainly in the west. The species involved were: Lucilia caesar, L. illustris, Protophormia terraenovae, Calliphora erythrocephala, C. vomitoria and Muscina pabulorum. Four of these species Lucilia illustris, Protophormia terraenovae, Calliphora vomitoria and Muscina pabulorum have not previously been recorded from sheep. Records of cases in which these flies occurred are given.

In June 1935 we observed in the intestine of an Indian squirrel, Sciurus sp.1, a coccidium which, since it has tetrazoic tetra-sporocystid oocysts, must be placed in the genus Wenyonella recently created by Hoare (1933).2

Difficulties encountered in the determination of species of Contracaecum from seals led the writer to undertake a comparative morpholgical study of a considerable amount of material. This included the Ascarids from seals collected by the Scottish National Antarctic Expedition (Scotia) in 1902–4, and deposited in the Royal Scottish Museum, Edinburgh, which were obtained on loan through the courtesy of Dr A. C. Stephen. In the present paper some results of this investigation are presented, and short notes are added on other species of Ascaridae recorded from Pinnipedia.

1. The reproductive cycle of the female fly was worked out at an average temperature of 24° C. The lowest egg of the right ovary develops first, and is ripe in 7 days. Ovulation never occurs earlier than the 8th day, and frequently later; it bears some relation to fertilization, for eggs in virgin females failed to ovulate for weeks. The first larva was produced in a variable time after fertilization (because of delayed ovulation), but the succeeding larvae were produced very regularly, with an average period of 9·9 days between them.

2. Pupae produced in the laboratory usually weigh less than those collected in the field. The reason for this is nutritional, and flies must take large meals at the right stage in gestation to produce large pupae. It is impossible to ensure that this happens with all flies in the laboratory.

3. Abortions are caused in captivity by flies obtaining too little blood. They may be induced in pregnant females by allowing them to take only small meals, when either an egg or a small larva is extruded. When these flies were properly fed later, they produced normal larvae.

4. A constant temperature of 30° C. causes sterility in females. Ovaries develop abnormally, embryos fail to hatch from eggs, but young larvae (in the uteri) are not adversely affected.

5. A constant temperature below 22° C. slows down the rate of development of the eggs in the ovaries and lengthens the larval period. Experiments at this temperature are complicated by inactivity of males, which leave many females unfertilized. The length of the combined embryonic and larval periods is 17½ days.

6. Experiments performed outside in the laboratory compound suggest that the period between each larva in the field (during December in Uganda) will be about 13½ days (min. temp. 16° C.; max. temp. 27° C.).

7. Flies appear to be able to breed equally well with relative humidities of 47, 88 and 100 per cent. In the drier air care must be taken with feeding, or the flies die from desiccation.

8. A temperature of 20° C. can cause pregnant females to retain their larvae for an extra 12 hours, but not longer.

During a visit to Tanganyika, thanks to the kindness and help of the Department of Tsetse Research, I was able to investigate the reproductive cycles in Glossina morsitans and G. swynnertoni, and compare them with the cycle in G. palpalis. In the previous paper in this Journal, Mrs H. N. Mellanby gives a detailed description of her work with G. palpalis, and the following comments on the similarity of the other species is all that is required.

Parasitology, Vol. 29, No. 1, 1937, p. 43.

Hoare, C. A. and Bennett, S. C. J. Morphological and taxonomic studies on mammalian trypanosomes. III. Spontaneous occurrence of strains of Trypanosoma evansi devoid of the kinetonucleus.

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