1. The longevity of the fasting larvae and nymphs of Hyalomma savignyi is investigated under different conditions of temperature and humidity.

2. It is found that both larvae and nymphs are much more sensitive to humidity than to temperature. Their longevity at low humidity is short as compared with that at high humidity at the same temperature. The longevity of the fasting larvae varies between very wide limits. The mean lenght of life varies between 1·25 and 162·6 days, whereas the maximum longevity obtained varies between 2 and 241 days, according to temperature and humidity.

3. The mean longevity of the nymphs varies between 6·8 and 149·2 days. The maximum varies between 10 and 246 days.

4. The relative dispersion of longevity varies within restricted limits under different experimental conditions.

1. In an alkaline inorganic solution containing borate, no bacterial disintegration of tissues occurs in a week.

2. Survival is prolonged by adding sugars to this solution, but not by the addition of bile salt or peptone. Monosaccharides are more effective than disaccharides, and both may enter the worm through its body wall.

3. The effect of variations in certain physicochemical conditions was studied. Wide ranges of osmotic pressure, of the K/Naratio, and of the Ca/Na ratio, have little effect on the worms. The optimum pH is c. 8.4, and t h e optimum temperature c. 36° C. Approximately anaerobic conditions decrease the survival time.

4. The effect of various bactericides, bacteriostatics and anthelmintics upon the worm were investigated in a preliminary manner. Many bactericides are toxic, certain anthelmintics are not. Survival is prolonged by 1/5000 trypan blue.

5. A satisfactory medium for large-scale ‘culturing’ is: NaCl 150 mM., KC1 10 mM., CaCl2 1 mM., borax 6 mM., glucose 30 mM. (pH 8.6). In this the worms survive for c. 60 hr. at a temperature of 36° C.

1. The adults of Fasciola hepatica feed mainly, if not exclusively, on blood.

2. The oxyhaemoglobin of the blood is converted to haemoglobin, and then to acid haematin, the pH of the empty gut being about 6·4.

3. The blood is concentrated by the removal of fluid, and haemolysis eventually occurs in the lumen of the gut. Some of the haematin is absorbed by the epithelial cells, and the remainder is concentrated as faeces.

4. The gut epithelium is responsible for extracellular digestion and absorption, but there is little evidence that the major changes in its appearance are associated with particular phases of this process.

5. Attempts at increasing survival times in vitro by using blood as food have failed to date because of bacterial contamination.

1. The egg shells of Fasciola are derived from globules or granules contained in the, vitelline cells. These globules contain an orthodihydroxyphenol and protein.

2. The anatomy and histology of the Mehlis's gland region have been described, and the site of liberation of the above granules has been isolated.

3. Mechanical forces, due to the churning action of the uterus, are believed to be responsible for freeing most of the granules. This liberation can be correlated with the presence of spermatozoa in the uterus. The spermatozoa can penetrate the vitelline cells, but this does not free the globules.

4. Active spermatozoa, in alkaline solutions, tend to form aggregates, and incorporate into these aggregates any solid material in the vicinity. This is apparently responsible for the arrangement of cells within the egg, and for the formation of a shell round it from fused vitelline cell globules.

5. The polyphenol of the newly formed egg shell is oxidized into a quinone in the anterior uterine coils. Polyphenol oxidases have not been conclusively demonstrated. The relative uterine coils are surrounded by an especial concentration of a generally distributed tissue haemoglobin.

6. The final egg shell is composed of a quinone tanned protein, similar to the sclerotin of the cockroach ootheca.

7. Suggestions are advanced as to the possible functions of Mehlis's gland and Laurer's canal.

1. Careful search has failed to disclose the presence of flame cells in the excretory system of the adult liver fluke.

2. Fat globules are produced in the walls of the excretory system, and are freed into the lumen, and thus to the exterior.

3. These globules do not contain appreciable quantities of cholesterol, cholesterides or lipins, but may contain some unsaturated fatty material.

4. The aqueous medium in which the globules float is either neutral or slightly alkaline.

5. The distribution of reduced ascorbic acid has been investigated by the silver nitrate technique. This indicates that the main concentration occurs in the smaller vessels of the excretory system, and in the submuscular tissues of the body wall.

Sporozoon Tincae Volf & Dvořak, 1928, is the cause of a fatal disease of the tench (Tinca tinca) in fish-ponds in south Bohemia. We can distinguish in its life cycle two different stages, multiplication by repeated binary fission, resembling schizogony and by sporogony with the formation of elliptical spores measuring 1.5–2 by 0.5–1 μ. The development of all these stages occurs in the cytoplasm of histiocytes. A detailed description of the life cycle is given. This parasite should be placed provisionally in the order Haplosporidia.

In 1941 work was started in North America with a view to introducing into South Africa parasite species which might act as factors in the control of the insect pest, Loxostege frustalis Zell. (Pyraustidae), which destroys large areas of Karroo bush (Pentzia incana), an important sheep-fodder plant in South Africa (Taylor, 1940). Several nearly related species of moths occur in North America, one of them being Loxostege sticticalia L., a serious pest of sugar-beet in the Great Plains region. A number of parasite species have been recorded from this host both in America and Europe (Pepper & Hastings, 1941), and it was thought that several of these species occurring in North America might be suitable for introduction into South Africa after their hiolocv and life histories had been investigated.

1. Chickens were infected with Coccidia, considered to be Eimeria meleagridis, from turkeys.

2. Turkeys were subsequently infected with oocysts obtained from the chickens.

3. Slight variation from normal measurements of the coccidia in chickens is attributed to development in an abnormal host.

4. E. acervulina from chickens was not infective to a coccidia-free turkey chick.

In an earlier paper (1933) the writer drew attention to the inadequacy of the only existing description of Uncinaria lucasi, given, under the name of Uncinaria sp., by Stiles & Hassall (1899). Through the kindness of Dr E. C. Dougherty, it has now been possible to examine specimens of an Uncinaria from the type-host of U. lucasi (the Alaskan fur-seal, Callorhinus alascanus). These were collected by Dr V. B. Scheffer, of the United States Fish and Wildlife Service, from the small intestine of a furseal pup at Polovina, St Paul Island (Pribylov group), in the Bering Sea in July 1945. There seems to be no reasonable doubt that they are of the same species as those originally described by Stiles & Hassall, the principal evidence being the identity of the host and locality, and the length of the spicules of the male worms. A new description is therefore presented, which it is hoped will place the species on a more satisfactory footing.

1. When sporozoite-induced infections of Plasmodium relictum are treated with atebrin (mepacrine) in doses suppressive to blood-inoculated infections, for periods exceeding that of normal incubation, parasites devoid of pigment appear in the erythrocytes of the peripheral blood. A small proportion of these may develop into schizonts, but the number of merozoites produced is fewer than normal.

2. A similar phenomenon occurs when quinine is substituted for atebrin, but the drug appears to be excreted more rapidly so that the inhibitive effect upon growth is less marked.

3. When plasmoquine is given in the maximum tolerated dose to birds infected with sporozoites, parasites are not seen in the peripheral blood during treatment, though the infection is not sterilized. With smaller doses parasites, including a few small schizonts, are found in the erythrocytes during treatment.

4. Merozoites produced in the erythrocytes during drug treatment are not capable of further multiplication when inoculated into uninfected birds having a similar blood-concentration of drug, so long as treatment continues, though they develop normally when transferred to untreated birds.

5. No indication of drug resistance has been observed.

6. The possible mechanisms by which blood-inoculated infections are eradicated, or resist eradication, are discussed.

We wish to thank Miss Vincent (Mrs Thorpe) and Dr Parr Tate for access to their preliminary unpublished experiments, and the latter for helpful criticism.

The plerocercoid larvae of the pseudophyllidean cestode Ligula intestinalie have been removed from the body-cavity of the roach, Rutilua rutilus, and cultured in vitro under aseptic conditions, using a technique similar to that successfully applied to Schistocephalus solidus.

In the larval condition, the genitalia are in a primitive, immature condition, with the testes, ovaries and yolk-glands only partially developed.

Larvae were cultured in peptone-broth in plugged tubes at a temperature of 40° C, i.e. the body temperature of birds in which the plerocercoids normally develop into adult worms.

Three of the nine larvae used became sexually mature after 7 days' cultivation, and oviposition took place. Copulation between successive genitalia of the same worm or with genitalia of another worm in the same culture tube was not observed.

Histological examination revealed that spermatogenesis, oogenesis, vitellogenesis and shell formation had apparently taken place in a normal manner. The testes contained giant polyploid cells as well as mature spermatozoa. The receptaculum seminis contained no spermatozoa, from which it was concluded that fertilization had not taken place. This was confirmed by the fact that attempts to hatch out the eggs were unsuccessful. The unfertilized eggs, however, underwent parthenogenic development within the uterus as far as the two-cell stage. Of the remaining six larvae, four developed sufficiently to undergo eversion of the cirrus, but died without oviposition taking place.