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.

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.

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.

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.

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.

Seasonal changes in the distribution of Lymnœa peregra (Müller) on a gently sloping beach of Loch Lomond have been studied in detail, with particular reference to the effects of the changes in water level which occur. At lower water temperatures the distribution can be correlated with the availability of food. At higher water temperatures the respiratory needs of adult snails cause them to remain close to the water's edge, even in the absence of food. This is not always true of young snails. Measurement of the fæces produced by such adult snails gives further evidence that a degree of starvation can occur for short periods in the summer months.

Comparative data on the characteristics of the physical environment and the general distribution of gastropods in Loch Lomond are given, and the study discussed in relation to previous work on the littoral ecology of large lakes.

The passage of ova down the Fallopian tube and uterine horn of one side into the horn of the other side is generally referred to as transuterine migration. There is evidence that such transmigration can occur in a wide variety of animals—Ungulata, Carnivora, Cheiroptera, Insectivora and Primates (Boyd, Hamilton and Hammond, 1944; Marshall's Physiology of Reproduction, 1952). In all these forms the genital tract has a single supravaginal segment varying from a common cervical canal to the single uterine cavity of the primate uterus simplex. The uterus of the albino rat is generally described as “uterus duplex”, with separate cervical canals opening independently into the vagina, and it has been stated by Hanson and Boone (1925, 1926) and by Slonaker (1927) that there is no evidence that transuterine migration occurs in the albino rat. In the course of an experimental investigation of the vascular pattern in pregnancy in the rat, some results were obtained which indicate that transuterine migration can occur in the albino rat.

The colour-pattern of hybrids between Ara chloroptera male and Ara ararauna female (Aves, Psittaci) combines parental features with a character which is found in some more “primitive” species of the genus but does not occur in the two parent species. The anatomical significance of this “ancestral” pattern mark is discussed.