An account of the morphology of the external and internal reproductive organs of the females of Hapalemur and Lepilemur and of the male of Hapalemur, including some histological details in both sexes of Hapalemur, is presented. The female apparatus in Hapalemur is described here for the first time, while new concepts emerge in connection with the male genitalia of Hapalemur and the female organs of Lepilemur, both of which have been imperfectly known. The tunnelling of the large clitoris by the urethra in Hapalemur is unique among the Madagascar lemurs and parallels the condition in the suborder Lorisoidea. The female Lepilemur exhibits typically lemurine external and internal genitalia, but lacks the glandular specialisations met with in Lemur. Details of the relative positions and peritoneal relations of the uterine cornua and ovaries in different lemurine genera are discussed. In the male Hapalemur the penis agrees with that of other Lemurinæ; internally some observations of Beddard and Oudemans are confirmed and supplemented. The necessity for the taxoaomic separation of Hapalemur is considered.

At a height of 4400 metres in the Nepal Himalaya, a vitreous and vesicular rock was discovered by J. S. Scott in 1949. It is located along a line of intense brecciation in a region of high-grade granitic gneisses.

This paper is based on a laboratory examination of a specimen of this rock and a few other specimens from the same locality. As some of these specimens have no exact counterpart hitherto described, a new but self-explanatory nomenclature has been employed in their description. The new rock-types—breccia with a cryptomylonite matrix, cryptomylonite and hyalomylonite—seem to represent, in this order, progressive stages in the degree of vitrifaction.

Biotite, alkali feldspars and quartz participated in the vitrifaction, which was due to high temperatures and heat developed by friction between these minerals in a triturated rock medium of low thermal conductivity.

An important function is attributed to the biotite which, in the more vitreous parts of the rocks, tends to disappear entirely. It is suggested that selective melting of this biotite has yielded to the liquid ferrous iron, and fluxing by this component is believed to be a critical factor although water must also be considered. Chemical analysis revealed no significant quantity of water in the glass-rich rock, but the development of vesicles and bubbles implies that there was more water in solution prior to its ebullition as a vapour phase.

There appears to have been a remarkable variation in temperatures within extremely short distances, and there is some evidence that the specific melting points of the alkali feldspars may, in a few exceptional instances, have been attained.

Fifty species of polychæte worms are listed which have not hitherto been recorded from the Clyde Sea area, and an account is given of the morphological differences which some of them show from the available descriptions. Of the fifty new records, nine are new to British waters, including one described as a new species, Amage scotica (Ampharetidæ).

The subjoined Note summarises an investigation into the skeleton of the pectoral fin of a common Selachian—Acanthias vulgaris—with the object of determining whether, and if so, to what extent it shows any vestige of the archipterygial type of structure. To this end careful examination was made of five hundred random embryos, and the result demonstrated the general occurrence of vestigial post-axial rays at the tip of the fin. The suggestion that such rays—stated by Braus to occur in a specimen of the embryo of Centrophorus—are to be regarded as a mere casual variation without evolutionary significance is thus shown to be devoid of weight, and the pectoral fin skeleton of Selachians established definitely in line with that of Pleuracanthus and Ceratodus.

Along with a note on Chonetes aff. edmundsi Williams and other associated fossils, nine new Lamellibranch species are described from what appear to be the Gutterford Burn Flagstones (Monoclimacis crenulata Zone), repeated by folding or thrusting, northwest of the North Esk reservoir and in the lower part of the Deerhope glacial-overflow valley, in the Pentland Hills. The localities occur respectively in the Midlothian and Peeblesshire parts of the Silurian sequence. The fauna represents an Upper Gala-Tarannon horizon, and is intermediate in age between Upper Llandovery and Lower Wenlock.

A survey has been made of the condition of the mantle cavity in populations of Lymnœa (Radix) peregra (Müller) and Physa fontinalis (L.) living in a range of depths and habitats in Loch Lomond. In many populations, including some in relatively shallow water, the mantle cavity remains water-filled throughout life. Where the cavity contains a gas-bubble, micro-gas-analysis (using a modification of Krogh's methods) has revealed that in some cases the gas composition is such that the bubble could be used as a physical gill, while in others such use is unlikely. Other observations on respiratory behaviour of the two species are reported, and growth-changes are noted in the surfaces available for cutaneous respiration. The study is discussed in relation to previous work on the respiration and ecology of freshwater pulmonate snails.

Recently discovered fragments of the armour of the ostracoderm Corvaspis are described, together with similar material from Vestspitsbergen and Podolia. The fossils have been obtained from Lower Old Red Sandstone deposits of Upper Downtonian–Lower Dittonian age. Large, thick, median plates, small irregular plates, orbital and ridge plates, and small, thick polygonal scales are present amongst the material. The characteristic external ornamentation of smooth, narrow ribs of dentine and a marginal band of small, smooth irregular tubercles is present on all plates. Two species are distinguished by their slightly differing ornamentation: Corvaspis kingi is known from the three regions named, C. graticulata sp. nov. comes from somewhat higher in the Vestspitsbergen sequence, and bears a finer ornamentation. A new family of heterostracans is erected to contain the genus, which in general structure may have been somewhat akin to the Drepanaspidæ, although no complete reconstruction can yet be attempted.

The concept of heritability is discussed in relation to the climatic changes which may affect the variations of age at sexual maturity in the fowl, and it is suggested that genetic and environmental variance, as expressed in the customary statistical formulation, may be largely synonymous terms.

Four groups of Brown Leghorn pullets are compared, one subject to no artificial lighting and the sub-optimal conditions of war years, a second to restricted lighting, and a third and fourth to 14-hour day length. The formal estimates of genetic and environmental variance were respectively 910 and 978, 594 and 546, 188 and 295, and 56 and 135. Further reduction of variability is apparent on subdivision into early and late hatches, heritability being apparently zero in the first case but maintained at an average level in the second.

Changes in variability substantiate the presence of genotype-environment interactions as previously reported, and similar conclusions follow from heterogeneity of regressions of age at maturity on date of hatch.

The inter-relationships of ten strains of blight (Phytophthora infestans) and four major genes, R1, R2, R3 and R4, controlling resistance to the disease in potato foliage are examined. The complete differential host series for this material numbers sixteen, and is capable of differentiating sixteen strains of the pathogen. The reactions exhibited by the series form a concise statement of the various relationships and provide a genetical basis for the systematic classification of strains. This classification affords a means of calculating the segregation-ratios to be expected from the mating of any pair of genotypes when infected with any strain or group of strains of the parasite.

Each strain, being adapted to a particular Solanum genotype, is more prolific on it than on any other. This genotype is regarded as the natural host of the strain in question. Specialisation, of the parasite appears to progress in stages in certain directions determined by the genetic constitution of the various hosts.

The nitrogen metabolism of both pods and seeds of Pisum sativum has been followed at sixteen stages of growth. The distribution of free amino acids and related compounds has been investigated by paper partition chromatography.

Over fifteen years (1935–49) no consistent change was evident in March egg numbers or the winter egg production of pullets to the end of that month. In birds with single-day interclutch gaps, however, the average March egg number showed an upward trend which paralleled the inverse curve for mean egg weight except during the war years. This improving performance of birds in full production was accompanied by an increasing variance among them. The proportion of pausing birds also increased over the years studied, but less regularly, and may have resulted from environmental causes. Two such contrary and apparently independent trends within a flock or line of fowls raise difficulties in assessing genetic changes which are occurring when the annual production is considered as a whole.

A detailed consideration of the morphology, peritoneal and topographical relations, blood supply and certain aspects of the histology of the alimentary tube are considered in these two rare lemurines, the anatomy of which has hitherto been very incompletely known. Evidence is presented of the structural apartness of Hapalemur from Lepilemur and Lemur and therefore for its separation in a separate subfamily of Lemuridæ. Differences between Hapalemur and Lepilemur are seen in the stomach, cæcum, colon, spleen, liver and gall-bladder. The resemblance of the spleen of Hapalemur to that of the marsupials proclaims its primitive status, while the fissuration and relative sizes of the main hepatic lobes show noteworthy differences in the two genera. In some respects Hapalemur approaches the Cheirogaleinæ, but cannot be included by definition within that subfamily.

Known amounts of the Rous No. 1 sarcoma virus were injected into the legs of chicks. The birds were killed, the legs extracted, and the virus content determined at intervals. Controls showed complete recovery of the virus by the methods used. After 16 hours the amount of virus was 1 per cent, or less of the injected amount, and this low level remained until about 70 hours, when an increased amount of virus suddenly appeared. This is taken to imply that, like the necrotising viruses, those of the fowl sarcoma multiply in the cell in a non-infective and probably disaggregated form. These times agree well with previous histological findings. The implications of such a method of reproduction are discussed.

The hoatzin (Opisthocomus hoaziri) embryos are of special interest because the species is the only representative of its family and sub-order, and is well known to possess important anatomical features comparable with the bird-like reptiles. Eleven hoazin embryos collected by Dr G. S. Carter in British Guiana have been examined. These range in development from a stage having nine mesoderm segments—equivalent to a fowl embryo of approximately forty hours' incubation—to a single specimen ready to hatch. The earlier embryos resemble the corresponding stages in the development of other birds, but the oldest embryo shows features characteristic of the type and has been dissected. Points in the anatomy of this specimen and their bearing on previous observations on hoatzin embryos are discussed.

The present report is submitted as an illustration of the utility of variance and covariance analysis in the detection of specific modes of inheritance in quantitative genetics.

The techniques are discussed with reference to the existence of sex-linkage, maternal effects, non-additivity, and the confounding of these. Comparison of variance components due to male and female parents has revealed marked evidence of sex-linked variation of egg weight in a population of Brown Leghorns, but no obviously associated variation of body weight. Subsequent analysis reveals large sex-linked covariance, and it appears that sex-linked variation of body weight is masked by non-additive effects.

Similar conclusions follow from regression analysis of offspring on parent. For egg weight there is marked dependence of offspring on paternal variation, whilst for body weight, heritability from regression analysis is substantially lower than that estimated from correlations between offspring, in accordance with the existence of sex-linked and non-additive effects.

The contrasting geological and topographical features of different regions of Loch Lomond and its watershed are reflected in the nature of the bottom deposits of the lake. This paper presents a survey of the lake bed with the object of determining the extent of its regional variety, and confirms the validity of regarding the lake as divisible into two primary regions. The two primary regions, “upper loch” and “lower loch”, are clearly distinct, but the case for the separation of part of the lower loch as a third, intermediate, region cannot be dismissed without further investigation. From a comparison of the bottom deposits, an attempt is made to show the advance in trophic state made by the lower loch over that of the upper.

Sedimentary structures in the greywackes of Peeblesshire, including graded bedding, cross-lamination and load-cast structures, are described and their origin discussed.

Petrographically the greywackes are poorly sorted sediments composed of a variety of minerals and rock fragments. The minerals include quartz, felspar, augite and horn-blende, mica and chlorite, while the dominant rock fragments are andesites, spilites, quartz-keratophyres and granites.

Three groups of greywackes are recognized according to their mineralogy. The first, the Pyroxenous group, contains augite and hornblende. Rocks of the second group, the Intermediate group, are without these minerals, while the third group consists of rocks rich in garnet—the Garnetiferous group. These mineralogical differences are reflected in differences in the chemical analyses of the three groups. From consideration of the chemical and modal analyses it is suggested that differences in source rocks have influenced the composition of the greywackes more than variations in the intensity of alteration due to weathering and transport.

It is concluded that the greywackes have been formed from the rapid erosion of a land mass largely covered by Ordovician volcanic rocks, but also with developments of lowgrade regionally metamorphosed rocks and others resembling Torridonian arkoses. Sedimentation features are due to accumulation controlled largely by the action of turbidity currents.

A study involving the effects of supplementary artificial lighting during the winter months upon a line of Brown Leghorn hens, reveals that the onset of the annual rest is delayed as a result of its use, and the tendency for onset of rest to become earlier in successive laying cycles is reduced.

The influence of time of onset in determining the duration of rest is higher in birds that commence their rest early than in those commencing later, resulting in a curvilinear relationship between these two parameters. A hypothesis accounting for this phenomenon is proposed.

The relative importance of age at onset of first annual rest in determining its duration appears to be negligible. This conclusion is based on an analysis of records pertaining to a generation of the same line which was hatched over an abnormally long hatching season, thus enabling the effects of “date” and “age” to be separated.

Thin sections of the spinal ganglion of the rat were cut and examined with the electron microscope. Two main types of nerve cell are described. Type A with equal electron density of nucleus and cytoplasm. The cytoplasm contains large aggregates of Nissl's substance discretely scattered throughout the cell, mitochondria and osmophilic granules. Type B with a “light” nucleus and a “dark” cytoplasm. The cytoplasm is closely packed and homogeneous so that it is difficult to separate out the various cytoplasmic elements.

There is a well-marked nuclear membrane about 500 Å thick and characteristic strawberry nucleolus.

The capsular cells are closely applied to the nerve cell with no intervening boundaries. A system of cytoplasmic filaments—the “endoplasmic reticulum”—is present in the intercellular regions.

There are nerve fibres with lamellated myelin sheath, axolemma, Schwann cells and Schwann membrane.

Testicular material from a Blue Whale (Balœnoptera musculus Rafinesque), a Fin Whale (Balœnoptera physalus Lacepède) and a Sperm Whale (Physeter catodon L.), obtained 6–24 hours after death in the Antarctic during the whaling season 1946–47, showed that the testes of the first two animals were in the resting state and those of the third animal were active. Despite being collected some hours after death, the material has allowed estimation to be made for the first time of chromosome numbers from spermatogonia and spermatocytes in the prophase stage. The diploid and haploid numbers approximate to 48 and 24 respectively. These results are discussed along with those obtained by Makino (1948), the first worker to record counts of cetacean chromosomes, in his study of freshly fixed material from Dall's Porpoise, Phocœnoides dallii (True). They support this worker in his view that the cytological evidence indicates that Cetacea and Ungulata derive from a common source.

Some observations on spermateleosis and cell inclusions in the Sperm Whale are given.

Regarding the breeding season, the findings of previous workers are supported for the Blue and Fin Whales. That the Sperm Whale dealt with in this paper was found to be sexually active in December is support of Harrison-Matthews' view that the species has no definite sexual season or cycle.