In feathers of a wide variety of unrelated birds non-iridescent blue and related shades are produced by structures. In these, each colour-producing cell of a barb medulla contains a cavity whose outline tends to parallel the cell-boundaries (‘polyhedral’ cavity).

This contrasts with the situation in some other birds with corresponding colour structures where each medullary cell contains a smaller ‘spheroidal’ cavity left by the pycnotized nucleus.

Three different processes of moulding polyhedral cavities are described which modify the thickness of the colour-producing cloudy medium and possibly represent independent evolutionary trends.

The Moray Firth has been intensively fished for many years and has been of great historic importance to the development of Scottish fisheries. The stocks of exploited species in the firth and their relations to other stocks in Scottish waters are described.

Exploited demersal species include haddock, cod, whiting, plaice and lemon sole. The firth is an important nursery area for plaice, and is the most important plaice spawning ground in the North Sea.

The Moray Firth is also an important nursery area for herring. Evidence suggests that these fish recruit to adult stocks in the Minch. In the early 1960s a pair trawl fishery for sprats started and the firth became the most important sprat fishing area in Scotland. However, recruitment of recent year classes has been too poor to sustain the fishery, which has now been closed in order to protect the juvenile heiring which were landed as by-catch.

The distributions of shellfish species are closely related to the bottom sediments. Landings have become increasingly important as the demersal and pelagic fisheries have declined or moved further offshore. The fishery on the Norway lobster is now of particular importance and the catch per unit effort data do not suggest any decline in stock size. Other exploited species include squid, scallops, crabs and lobster.

Description of a little known anonymous pamphlet, an “Abstract” of the paper read before the Royal Society of Edinburgh, in 1785, in which James Hutton first announced publicly his famous Theory of the Earth. Reasons are advanced for concluding that Hutton himself was the author of the “Abstract”, and that it was published in 1785, some three years before the Royal Society paper was issued in the Society's Transactions. The writer concludes that the “Abstract”, and not, as has hitherto been supposed, the Transactions paper, constitutes the first form in which The Theory was published. The “Abstract” is reprinted in small type on p. 380.

An understanding of the movement of a body of water can be considered a prerequisite to any other study whether it be physical or biological. This is particularly so in the case of an estuary where the water movements are complex. The movement of water in an estuary is primarily governed by the tidal and freshwater inputs, the resulting flow being modified by bed and channel configurations, salinity, and siltload variations. The tidal and freshwater inputs are themselves variables, the tidal range varying with the lunar cycle, and the freshwater input varying with the season or rainfall. The salinity variations within an estuary are interlinked with the tidal and freshwater fluctuating inputs. In addition the local and regional weather can modify the tidal response.

A typical poultry flock consists of offspring from a number of sires each mated to several dams. In choosing male parents in a selection programme no criterion of individual merit may be available and selection must usually be based on the performance of related females. The present report deals with the theoretical efficiencies of three systems of selection of males

(1) on the average performance of the dam family of a male's sisters.

(2) on the average performance of the sire family of a male's full- and half-sisters.

(3) on a weighted combination of sire family and dam family averages.

For traits of low heritability system (2) may offer marked advantages over system (1), the only type of family selection previously investigated. This should prove of importance in flocks where recording facilities are limited. Providing environmental effects can be minimised, efficient selection may be based on the average performance of sire families housed as units without individual recording.

The efficiency of system (2) declines with increasing heritability and is also subject to complications introduced by population size. In all cases, however, optimum gains may be obtained on system (3) when both dam family and sire family records are available.

Water economy is a necessary complement of terrestrial life, for the limits of life upon land are, in part, determined by the organism's ability to utilize and conserve the water of its environment. For small organisms of terrestrial habit, the large surface-to-mass ratio and consequent surface evaporation makes the problem of water conservation particularly acute. It is therefore remarkable that the insects constitute the most numerous and varied group of terrestrial animals; and it follows that their success is, in large part, due to their ability to utilize and conserve water in widely divergent environments.

The dependence of plant production in the sea on the presence of nutrient salts, especially nitrate and phosphate, and on illumination has been repeatedly demonstrated. The object of the present work was to find primarily whether, and to what degree, plant and animal production could be increased by adding fertilizers to an enclosed body of sea water under otherwise natural conditions.

Genetic variation within a crop species is often limited and restricts improvement by conventional breeding methods. This is particularly true for environmental stresses, both biotic and abiotic. Wild relatives of crop plants, however, provide a rich source of novel variation which can be introduced into the crop. Many alien genes for biotic stress resistance have already been introduced into crops; in contrast, the genetic control of abiotic stress tolerance is poorly understood. Genetic engineering of abiotic stress tolerance in the Triticeae is the main subject discussed here with particular reference to salt tolerance in wheat and barley. Methods of alien gene transfer, including locating tolerance genes and restructuring chromosomes, are described. One of the major limitations in transferring genes for stress tolerance is the lack of good tests for resistance or tolerance which is largely due to the fact the physiological mechanisms involved are not fully understood. Genetic markers provide a new opportunity of detecting chromosome segments carrying desired genes easily and efficiently, and these will become increasingly important as the genetic maps of crop species are expanded. Although many stress genes have been located to specific chromosomes, and some have been mapped intra-chromosomally and their dominance relations determined, there is a great lack of knowledge of the control of these genes at the molecular level. Molecular studies of this type are difficult, but it is anticipated that the limitations will be overcome in the near future.

The aquatic fern Azolla has a symbiotic relationship with an N2-fixing cyanobacterium. Fanners in China and Vietnam have used Azolla for centuries as a green manure for rice and as fodder for pigs, ducks and fish. Chinese researchers have been studying Azolla since the early 1950's but many of their achievements are unknown outside China because of language and other communication problems. This article reviews current Chinese Azolla research and focuses on the impact of newly introduced Azolla species in the areas of field application, use of spores, and isolation of the N2-fixing symbiont.

Phenolic secondary compounds and trichomes are instrumental in the regulation of herbivory on Salicaceae. The roles of phenolics in willows as toxins or deterrents, as phagostimulants or ovipository signals, and as precursors in insect chemical defence are briefly reviewed. The interactions between salicaceous plants, herbivores and their predators are discussed in the context of theories on the evolution of interactions among three trophic levels.

Like the world's oceans themselves, the Challenger Expedition overwhelms us by its vastness. In whatever direction one turns, the statistics speak of a copiousness, a completeness comparable to the other monuments to Victorian self-confidence. Challenger's cruise lasted 41 months; in 710 days at sea the ship travelled 69 000 miles around the globe on 4600 tons of coal. The ocean bottom was sounded 370 times, 255 serial temperatures were taken, and from the hauls of trawl and dredge at 240 stations came 600 cases of specimens animal, vegetable and mineral [2]. The 50 royal quarto volumes published over 16 years make the Report on the Scientific Results of the Voyage probably the major single research project of all time, with their nearly 30 000 pages of letterpress and more than 3000 lithographic plates, 200 maps and copious woodcuts. For more than two decades, from its announcement at the British Association meeting of 1871 to the banquet held to commemorate the publication of the final volume in 1895, the Challenger Expedition and its Report occupied the entire lives of some dozen men and substantial portions of the lives of many hundreds more.

The growth and development of Sitka spruce roots is reviewed against the practical background of tree stability. Two features of the roots which make Sitka spruce liable to windthrow on upland sites are the shallow development in unfavourable soil conditions, and restricted lateral spread and anchorage caused by some forms of cultivation. Responses to different aspects of the soil environment are discussed, with emphasis on mineral nutrition, drying of the soil, waterlogging and temperature. The development of a small number of major woody roots from an assortment of primary laterals on the transplant occurs at an early age and is determined both by the relative size and vigour of the primary roots and by their local environment. The roots, which respond to increases in nitrogen and phosphorus supply with enhanced growth, are sensitive to drying of the soil and are particularly so to waterlogging, but they show no unusual response to soil temperature. Adventitious roots can play a role in the survival and development of the root system.

The status of insects on Sitka spruce in Britain is examined in relation to the attributes of this tree as a widely planted exotic. Both time in Britain and particularly the area planted influence insect species diversity. The abundance and status of selected insects of pest importance are examined. Future trends receive attention, particularly in relation to potential importation of pest insects and this is examined for a number of species from Europe and North America.

The morphological variation between and within species of Betula has resulted in taxonomic confusion which chromosome studies have been aimed at reducing. The paper briefly reviews the general situation and summarizes recent work at Aberdeen.

Betula forms a polyploid series with chromosome numbers ranging from 2n = 28 to 2n = 84. The native British arborescent birches B. pendula and B. pubescens Ehrh. have respectively 2n = 28 and 2n = 56 chromosomes. Meiosis is essentially regular but many phenomena occur which may account for the production of gametes with non-haploid chromosome numbers. Variation in somatic chromosome number within the leaf tissues of both species is common and trees have been identified whose modal chromosome counts lie between 28 and 56. Some of these trees are of hybrid origin while others may aneuploid B. pubescens. The former types are sterile while the latter cross freely amongst themselves and with 2n = 28 and 2n=56 trees.

Bracken, Pleridium aquilinum, has long been present in Britain as part of the native flora. Before the arrival of man, Britain was a wooded and forested country, and in this vegetation bracken was an open woodland and forest margin species, which played only a relatively minor vegetational role. Its biology is such, however, that this plant is able to spread rapidly in response to removal of the forest canopy, developing into colonies which are much more ecologically aggressive and dominating than was the original habit of the plant when undisturbed.

In open conditions, bracken also has a far greater spore output than in more shaded ones. It is able to establish anew from spores only in relatively virgin soil conditions, particularly those produced by burning of other vegetation. Burning also benefits established bracken by removal of its competitors, whilst heavy and selective grazing by sheep also slowly reduces the natural vegetation competition in favour of bracken's further spread.

The history of the spread of bracken in Britain from palynological and historical evidence is reviewed in the light of this biology and, in particular, its spread as man has progressively removed the forest canopy,introduced steady heavy grazing pressure, and has burned, and continues to burn, vegetation.

The fishery for Norway lobsters Nephrops norvegicus began in the 1950s and has since become one of the most valuable assets of the Clyde Sea Area. Landings of Nephrops reached a peak of 26001 in 1972. Following a decline in landings up to 1975 there has been a further increase to over 45001 in 1983, valued at £4–5 million. Most of the landings are made by inshore trawlers working from Ayr, Troon, Girvan, Largs, Campbeltown and Tarbert. Recently a small creel fishery has developed in some sea lochs. The abundance of the stock appears to have been maintained; landings per unit of fishing effort have fluctuated without any obvious trend.

Since September, 1979. several aspects of the biology of Nephrops have been studied in an area south of the Little Cumbrae at the north end of the east Arran Basin. Data are presented on the density, size composition, growth rate, reproductive biology and feeding of Nephrops in this area. The results are compared with those obtained for other Nephrops populations, revealing some unusual features of Clyde Nephrops. In the Clyde, densities were lower than in a number of other areas, while growth rate was much higher and animals grew to larger sizes. Sexual maturity was attained at a larger size in Clyde Nephrops and studies of ovary development revealed that considerable numbers of large females did not reproduce annually, in contrast to some other areas. Recent observations suggest that the biological characteristics of Nephrops populations in an area may be influenced by features of the local physical environment such as the particle size distribution and organic carbon content of the sediment. Differences between Clyde Nephrops and those from other areas are discussed in relation to this.

Red deer, sheep and reindeer grazing on their normal hill ranges were examined at intervals over a period of four years. Samples from the digestive tract were taken at different seasons and processed in the field. The Red deer and reindeer were killed before samples were taken; rumen samples from the sheep were taken by stomach tube, but a number of animals were also killed at different seasons to correlate stomach tube and whole rumen samples. The animals sampled were representative of the general condition of the herds. Examinations were made for parasites and any pathological conditions. In most instances parasitic infections were slight. Apparent seasonal changes were found in the compositions of the diets. The Red deer and sheep ate principally heather and grass, the proportion of heather increasing in the winter. The reindeer ate mainly grass in the summer, with lichens and grass forming the winter diet, and these animals seemed to have a higher nutritional status in the winter than did the other two species. The weights of the animals and of their rumen contents, the concentrations of rumen ammonia and volatile fatty acid, and the rates at which different dietary components were fermented are recorded. Rumen fermentation was low in winter and the diets were generally inadequate for the animals. A lack of nitrogen seemed to be a major factor.

Some data on caecal contents are also given.

Material of a very small and distinctive species of Isoetes was sent by Miss Alison Baird in 1934 to Professor J. Walton, who kindly handed it over to me for examination. This species, hitherto undescribed, is here named Isoetes australis. The material, which consisted of plants of all ages from two-leaved sporelings up to adult plants, had been collected in 1930 from rock pools in granite outcrops at Bruce Rock, 150 miles inland from Perth, Western Australia.

The following description is mainly based on Miss Baird's material, but I later received air-dried plants of the same species which had been grown by Professor T. G. B. Osborn in the Laboratory at Sydney. These plants had originally been collected by E. T. Bailey from the Bruce Rock locality in 1934. They proved to be viable and commenced growth within a few days when placed in water, and I was able to keep one of them alive for a period of two years, though only in a depauperate condition. Professor Osborn also sent me herbarium specimens, collected in the same locality by Bailey, and some of these plants, which had been completely dry for six months or longer, proved viable, though I was unable to grow them on for more than a few months.

Crop protection against pests and diseases is of prime importance and plays a major role in agricultural production both in the Developed and Developing parts of the world.

Although chemical pesticides have been in use for a long time it is only since the Second World War that a very heavy and almost exclusive reliance has been placed upon their use. This, in many cases, has resulted in the rapid build-up of resistance by insect pests to such compounds, as is illustrated by the rapidly developed resistance to the organochloride insecticides by the cotton bollworm, Heliothis virescens. Indeed, there are many examples of resistance in a major pest being observed within the first year of field use (Metcalf 1986). In some cases the indiscriminate application of pesticides has exacerbated the problem of insect herbivory where elimination of a wide range of predatory species along with the primary pests has resulted in secondary pests becoming primary pests themselves with even more devastating effects (Heinrichs & Mochida 1983).

The hypothesis of reed decline being a consequence of eutrophication has been proved. Rhizomes of P. australis from two habitats differing in nutrient availability were collected during one year. In the nutrient-poor habitat, less aboveground biomass and greater starch reserves were formed in comparison with the nutrient-rich one. In the stand with a high nutrient availability, a decrease in starch content was observed in horizontal rhizomes during autumn.