During the course of Mr J. M. Wordie's Arctic Expedition in 1937 the first-named writer (H. I. D.) visited three localities in the Tertiary Igneous Province of West Greenland. Small collections were made at each locality.

Only very little geological work could be undertaken on this Expedition owing to the very heavy programme of work in other scientific fields, one of its main objects being cosmic-ray research. The collections on which this paper is based were the result of very rapid, very superficial field-work.

During the late war Mr Bruce Taplin received for mineralogical investigation a low-grade cassiterite concentrate from a small plant operated by the Non-Ferrous Mineral Development Control (Ministry of Supply) for the recovery of wolfram from the eluvial and alluvial gravels of the valley east of Buttern Hill, near the northern margin of the Bodmin Moor granite (fig. 1). As received, the sample contained 4·1 per cent, of tin.

Studies in the variation of the Anthracosiidæ (= Carbonicolidæ) in the South Wales Coalfield by Davies and Trueman (1927) and in the Scottish Coalfields by Leitch (1936, 1940, 1941) have suggested that environmental influence on shell form is confined to changes in thickness of shell and in obesity. Davies and Trueman quoted H. R. Wakefield, who remarked that to-day among the Unionidæ these characters appear to vary according to the station of the shells in a single lake. Leitch referred to the work of Ortmann (1920) on the relation between obesity and distribution of river mussels in a large drainage basin in the U.S.A. The writer, in the course of very detailed work on the most highly variable faunas of the Anthracosiidæ known in the British Coal Measures, found evidence suggesting that certain other changes in shell shape and dimensions may also accompany environmental changes, as far as past environments may be reflected in the lithology of the rocks containing the shells.

It is common knowledge that during the period 1875–1939 a very drastic fall in fertility occurred in most of the civilised countries throughout the world. This fall was particularly marked in Germany and some of the countries of North-western Europe, such as Norway, Sweden, England, Scotland, etc. The causes which have produced such important changes in the rates of reproduction in these communities are doubtless complex, and are difficult to investigate directly. It is therefore all the more important that our knowledge of the actual course of events should be as complete as possible. A major social change, such as this fall in fertility over large and important regions of the earth, can be fruitfully studied from many points of view. The present communication concentrates on one particular aspect, namely the influence of different types of geographical regions with their various social environments, and confines itself to the experiences of Scotland.

The apparatus which one selects for the study of gaseous exchange by living tissue is largely determined by the nature of the problem with which one is confronted. Choice usually lies between those methods where a continuous stream of air is passed over the respiring material and alteration in its carbon dioxide content measured, or those in which the oxygen or carbon dioxide content of the air surrounding the respiring material in a closed system is periodically determined. The former system is frequently used when one is only concerned with relatively large quantities of carbon dioxide. The gas, which is usually absorbed by passing the air through solutions of sodium or barium hydroxide contained in Pettenkoffer tubes or Reiset towers, may be subsequently determined by titration of the alkali with standard acid. This arrangement is much used owing to the readiness with which it may be set up employing normal laboratory equipment. The labour involved can, however, be considerably curtailed by adopting the electrical conductivity method for determining carbon dioxide. This has been described by Newton (1935). It may be made more accurate and more sensitive than the titration methods and, moreover, enable determinations to be made quickly and at short intervals of time. Leach (1944) has made the method automatically recording.

In his work on the “Present Evolutionary Tendencies and the Origin of Life Cycles in the Uredinales”, Jackson (1913, p. 7) has pointed out that the general impression among mycologists, until quite recently, has been that the life cycles in existing species of rust are quite definitely fixed. In a review of the small amount of literature that has appeared on this subject, he has shown that this conception is not altogether true, and that it is not at all difficult to find species of rusts which exhibit evidence of being in an unstable condition with reference to life-history. As the literature which he has quoted is almost exclusively American and deals with American species only, it might be inferred that this instability of life-history is not found elsewhere. The purpose of this paper is to review the European literature on this subject, and to describe the occurrence in Great Britain of four rust species of which the life-history is in an unstable condition.

The present paper gives an account of the behaviour of the Golgi material, mitochondria, and nucleolar extrusions during the oogenesis of dog, cat, and rabbit. So far as the writer is aware there is no previous detailed work on the cytoplasmic components of the female germ-cells of the animals investigated.

R. Vander Stricht (1911) dealt with the oogenesis of the cat; O. Vander Stricht (1923) has made a comparative study of oogenesis of mammals, including the dog and the cat; P. del Rio Hortega (1913) described the behaviour of the Golgi material, and H. von Winiwarter (1900) studied the nuclear changes during oogenesis of the rabbit; H. von Winiwarter and G. Sainmont (1909) dealt with nuclear metamorphosis during the oogenesis of the cat; finally J. Nihoul (1926), in his paper on the rabbit, described the Golgi material during oogenesis. All the papers quoted, apart from those which deal with the nuclear changes, are either incomplete surveys, or the methods used are insufficiently delicate to reveal changes shown by modern techniques.

The South African clawed toad, Xenopus Iœvis, ovulates and extrudes its eggs into the water after injection of gonadotropic extracts (Hogben, 1930). Xenopus has been shown to be a most satisfactory test animal for the detection of chorionic gonadotropin in the urine of pregnant women, provided the toad is in good condition. In the last ten years much work has been done on the husbandry and breeding of these animals and good laboratory conditions specified (Alexander and Bellerby, 1938; Landgrebe, 1939; Landgrebe and Purser, 1941; Gasche, 1943; Landgrebe and Samson, 1944). This toad has many advantages over other test animals. It lives indefinitely in the laboratory; the author has kept some animals for over twelve years, and they still respond to injection of gonadotropic extracts by ovulation and extrusion of eggs into the water. Recognition of this response does not necessitate killing the animal. Since Xenopus never ovulates spontaneously under normal laboratory conditions and does not extrude all its eggs simultaneously after an injection of gonadotropic extract, it can be used repeatedly. Each toad can be used at least twenty-four times under the conditions specified. The animals can be kept in good condition without much demand on laboratory routine. They need feeding and cleaning only once a week. The toads are very viable. Apart from the few deaths which often occur soon after a new stock arrives in this country, the writer has lost only eight animals in the last three years, during which time the average number kept was 500 and the number of test injections exceeded 5000. If kept at 22° C. the normal animal in good condition ovulates and extrudes eggs into the water within 24 hours after the single large dose of gonadotropic substance used in routine pregnancy diagnosis. These advantages, and the possibility of realising a simple 24-hour quantitative assay of chorionic gonadotropin, prompted an investigation into the use of the toad as a test animal for this purpose. Necessary preliminaries include inquiry into the effect on sensitivity of (1) temperature, (2) light, (3) weight of animal, (4) repeated use, and (5) route of injection. These points have been investigated with a view to the discovery of the most important variables. All the animals used have been in captivity for many years, and had previously been used many times for routine Hogben tests for pregnancy.