Model scale tests of modern ‘open rotor’ propulsor concepts that have potential for significant fuel burn reduction for aircraft applications were completed at NASA Glenn Research Center. The recent test campaign was a collaboration between NASA, FAA, and General Electric (GE). GE was the primary industrial partner, but other organisations were involved such as Boeing and Airbus who provided additional hardware for fuselage simulations. The open rotor is a modern version of the UnDucted Fan (UDF®) that was flight tested in the late 1980s through a partnership between NASA and GE. The UDF® was memorable for its scimitar shaped propeller blades and its unique noise signature. Design methods of the time were not able to optimise for both high aerodynamic efficiency and low noise simultaneously. Contemporary CFD/CAA based design methods can produce open rotor blade designs that maintain efficiency with acceptable acoustic signatures. Tests of two generations of new open rotor designs were conducted in the 9’ × 15’ Low Speed Wind Tunnel and the 8’ × 6’ Supersonic Wind Tunnel starting in late 2009 and completed in early 2012. Aerodynamic performance and acoustic data were obtained for take-off, approach and cruise conditions in isolated and semi-installed configurations. Additional detailed flow diagnostic measurements and acoustic measurements, including canonical shielding configurations, were obtained by NASA. NASA and GE conducted joint systems analysis to evaluate the performance of the new blade designs on a Boeing 737 class aircraft. The program demonstrated a 2-3% improvement in overall net efficiency relative to the best efficiency designs of the 1980s while nominally achieving 15-17 EPNdB noise margin to Chapter 4 (at a Technology Readiness Level of 5) for a notional aircraft system defined by NASA.

The science of extra-solar planets is one of the most rapidly changing areas of astrophysics and since 1995 the number of planets known has increased by almost two orders of magnitude. A combination of ground-based surveys and dedicated space missions has resulted in 560-plus planets being detected, and over 1200 that await confirmation. NASA's Kepler mission has opened up the possibility of discovering Earth-like planets in the habitable zone around some of the 100,000 stars it is surveying during its 3 to 4-year lifetime. The new ESA's Gaia mission is expected to discover thousands of new planets around stars within 200 parsecs of the Sun. The key challenge now is moving on from discovery, important though that remains, to characterisation: what are these planets actually like, and why are they as they are?

In the past ten years, we have learned how to obtain the first spectra of exoplanets using transit transmission and emission spectroscopy. With the high stability of Spitzer, Hubble, and large ground-based telescopes the spectra of bright close-in massive planets can be obtained and species like water vapour, methane, carbon monoxide and dioxide have been detected. With transit science came the first tangible remote sensing of these planetary bodies and so one can start to extrapolate from what has been learnt from Solar System probes to what one might plan to learn about their faraway siblings. As we learn more about the atmospheres, surfaces and near-surfaces of these remote bodies, we will begin to build up a clearer picture of their construction, history and suitability for life.

The Exoplanet Characterisation Observatory, EChO, will be the first dedicated mission to investigate the physics and chemistry of Exoplanetary Atmospheres. By characterising spectroscopically more bodies in different environments we will take detailed planetology out of the Solar System and into the Galaxy as a whole.

EChO has now been selected by the European Space Agency to be assessed as one of four M3 mission candidates.

Observations on breeding (1, 1914; 2, 3, 1920) and experiments on the rate of growth of marine invertebrates (4, 1914; 5 to 9) have been carried out since 1911 (excepting the war period).

The gonads of 1,121 oysters have been examined at various periods from a few hours to twelve months after the individuals had spawned as females; the material for the research was obtained by collection and experiment. In 702 individuals taken with young in the mantle cavity the gonad shows a progressive development of maleness in its primary sexual characters; within a mean period of 2¼ hours after spawning eggs, the gonad was found in 50 per cent of cases with only young spermmasses developing, followed at later periods by a progressive ripening of the sperm-masses, until in individuals carrying shelled and black-coloured larvae 77 per cent contained abundant ripe sperm-masses as well as advanced developing sperm-masses.

In 444 individuals examined at various periods after extruding their larvæ, the development of sperm was found to continue for about a month after egg-spawning, and to abate in about the second month. In from 2 to 3 months after egg-spawning sperm-development is completed and the male phase begins to wane, and a small percentage of individuals may become female or actively female-functioning again. In 12 months after the last egg-spawning a significant number of individuals become once more functional females.

The varieties of mixed sexes found in O. edulis are denned and their frequencies shown by an analysis of samples—from two widely separated beds—examined at the beginning of the breeding season in 1926. Experiments on the rate of growth of sperm-masses and on determining of age at different stages of development in embryos and larvæ are given.

The small individuals were examined before the height of the breeding season, and there is a probability that many or most of the indeterminate individuals would become male. Hermaphrodite individuals have been observed previously, and in certain samples 10% of the males contain doubtful young ova in the gonad. It is therefore concluded that Patella vulgata is apparently a protandric hermaphrodite, but that the evidence is not yet sufficiently good to prove protandry.

It is suggested that possibly two kinds of male, which may be recognisable by chromosome constitution, may occur, one being pure male and one protandric, and also that sex-change may be controlled by as yet unknown metabolic conditions.

The breeding period is discussed ; it may extend from August to March at Plymouth in different seasons, and spawning may occur within this period. A maximum of spawning appears to occur about January-February. The conditions controlling breeding and spawning in Patella are unknown, and as the course of seasonal shell-growth is unknown, although shell-growth is general at the end of the breeding season, it is suggested that research on the subjects in the future should be combined.

While working on the beds in the River Blackwater, Essex, a collection of Portuguese oysters, which had been dredged along with native oysters (O.edulis) from the river and creeks, was seen at a glance to show a distinct average difference in shape from the usual type of Portuguese oyster. The ordinary Portuguese oyster as seen exposed for sale is usually im-ported when quite small, or occasionally well-grown, and relaid on English beds at or above low-water mark to grow and fatten. Orton* has shown by definite experiments on the same beds that the Portuguese oyster spawns and spats in English waters in favourable (hot) weather. There can be no doubt, therefore, that the Portuguese oysters dredged had grown in situ from larvae which had developed in the waters of the river and creeks. In Portugal and France the Portuguese oyster is stated to occur at and just below low water springs (see Bashford Dean, Bull. U.S.F.C. XI, 1891 (1893), p. 368), and is apparently hand collected at the present day for export purposes.

A difference in shape in native oysters is very common, but Bell and others have so far found it a very difficult matter to correlate any particular shape with a particular environment. Indeed, Bell stated, in a letter, that each locality seems to have its own type of shell-growth in the native oyster. Such a difference as that noted above in the Portuguese oyster was therefore deemed worthy of some attempt at expression.

Continuous observations on the Upper Fal Estuary oyster beds during the years 1925, 1926, and 1927 have established the fact that 0. edulis exhibits on these beds two definite periods of shell-growth, i.e. increase in shell-area, in one year; one period of general shell-growth occurs in the spring, beginning early in April, and the other in autumn at the end of September or early in October. There is some evidence-but as yet incomplete-that internal shell-growth occurs solely and simultaneously with the deposition and thickening of the new shell-shoots in a period of one to two months.

These general bursts of shell-growth occur in the pre-breeding and post-breeding part of the season

Similar periods of shell-growth occur on beds in the River Blackwater (AVest Mersea), and also occur mainly in the pre-breeding and postbreeding part of the season; but shell-growth begins in the spring in April-May on these beds, a few weeks later than on the Upper Fal Estuary, and in the autumn in August-September a few weeks earlier than on the Upper Fal beds.

Spring and autumn periods of shell-growth are also known to occur on many other estuarine beds.

The results of the writer's investigations on the ciliary mechanisms on the gills of Mollusca and Amphioxus (1 and 2) gave rise to the suggestion that similar mechanisms might probably also occur in Brachiopods, for it is a well-known fact that Brachiopods—like some Molluscs and Amphioxus—feed on the smaller organisms which are to be found floating in the sea. Owing to the kindness of Dr. H. C. Williamson, of Aberdeen, I have been able to examine living Crania which were obtained by dredging in Loch Fyne, and living Terebratula have also been obtained from Naples. An investigation of the living gill-filaments—or lophophoral cirri, as they are frequently termed in this group—showed that the ciliary mechanisms on these filaments are essentially the same as those occurring on the gill-filaments of Amphioxus, Lamellibranchs, some Gastropods, and most Ascidians. As it was found that existing accounts of the mode of feeding in Brachiopods are vague and incomplete the following description of the process has been written.

The observations recorded form preliminary studies which it is hoped will be useful in special investigations on the physiology of shell-depositions in oysters. The distribution of chalky shell-deposits on the internal faces of the valves in young and old O. edulis and O. angulata has been studied, and its average distribution determined in shells of O. edulis of jnedium age from West Mersea and the Fal Estuary.

The distribution of this material in the shells of young O. edulis and in O. angulata is such that there can be little doubt that the function of the chalky deposit is to fill in rapidly grooves, hollows, and other spaces, which are inimical to efficient functioning in the changing needs of the individual.

In O. edulis of medium age large deposits occur regularly in the shell adjacent to the exhalent chamber and smaller ones on the border of the shell in the region of the inhalent chamber. The hypothesis is advanced that these regular deposits can be explained in the same way as those more easily understood by assuming that in a high percentage of shells of medium age, the contour of the shell in the region of the exhalent chamber and other parts is such that rapid extension and contraction of the mantle cannot be effected; deposition of chalky shell-material modifies this contour of the shell with certainty in some cases, but hypothetically in others, so that the mantle can be extended and retracted with a maximum of efficiency.

The breakwater in Plymouth Sound offers a simple case of two adjacent populations ofintertidal organisms subjected to quite different degrees of exposure to wave-action. The other environmental factors, with a few exceptions, are approximately the same each side, and the effects of the wave-action should be clearly demonstrable.

From experiments in the sea with wire cages and boxes with perforated zinc sides and tops more than 100 individuals of certain Crustacea which had grown inside the apparatus have been obtained at various subsequent dates.

Minimal mean rates of growth are obtainable from the difference between maximum size at immediate entry and size at a given later date, and the approximate age by an allowance for age at entry plus the maximum time occupiable in the experimental apparatus. It was found that C. maenas spawned early in the year may attain a carapace width of 30 to 40 mm. by the following winter. In experiments extending over twelve months from July to July male C. maenas attained a carapace width of 43 to 53 mm. and females 37 mm. at an estimated maximum age of 15 months.

An analysis of the quantity and distribution of unspawned eggs in the gonad of o. edulis recorded in Table IV, 1, 1927 (of oysters with young) and Table IX, 1,1927 (of post-spawned oysters), gives useful information regarding the occurrence and fate of unspawned ova as may be seen from the figures given in Table A.

A hermaphrodite specimen of Amphioxus has been taken at Plymouth having one gonadial pouch filled with ova and the remaining pouches filled with sperm. This specimen closely resembles a similar one taken by Goodrich at Naples.

The liver and intestine of the Plymouth specimen are abnormal, but no parasites have been identified in the tissues to account for these abnormalities.

It is, moreover, improbable that there is any normal sex-change in Amphioxus, since three independent investigators have found very small specimens of both sexes, therefore no satisfactory explanation can be given of the occurrence of hermaphroditism in the specimen.

Amphioxus have been found to spawn in June, and larvae have beenobtained from the captive specimens.It is suggested that the club-shaped gland may secrete a substance for attaching the larva of Amphioxus to objects, and that this function may be correlated with the asymmetry shown in the early development of the Amphioxus .larva.

[The following Tables record the measurement and enumeration of a number of characters in certain samples of Herrings taken in the neighbourhood of Plymouth. The work was carried out as part of a general scheme for studying the question of the existence of local races of herrings around the British Coasts, which was organised by the Board of Agriculture and Fisheries. In consequence of the war there is no immediate prospect of the figures being analysed and compared with similar figures relating to fish obtained in other localities. It has therefore been thought advisable to place them on record as they stand, so that they may be available for other workers at any time. The short explanatory statement of the methods employed was prepared by Dr. Orton, who had charge of most of the work, to accompany the figures when they were sent to the Board of Agriculture and Fisheries, and was not written by him with a view to publication. The drawings have been made by Mrs. Sexton.—E. J. Allen.]

The mode of feeding in Amphioxus is effected by–

(1) The maintenance of a stream of water through the pharynx by rows of lateral cilia on the gill-bars.

(2) The throwing out of mucus from the endostyle on to the gill-bars to serve for entrapping food-particles.

(3) The collection of food-particles by rows of cilia on the pharyngeal surface of the gill-bars; these cilia woraSkip the foodparticles with mucus into cylindrical masses and transport such masses dorsally into the dorsal groove which carries the collected masses backwards into the digestive tract.

Thus the ciliary mechanisms on a gill-bar of Amphioxus are exactly the same as those on the gill-filaments of some Lamellibranchs, as Pecten, and some Gastropods, as Crepidula.

A subsidiary mode of food-collection is effected in the buccal cavity of Amphioxus by the ciliated tract known as the wheel organ, and Hatchek's pit, which supplies mucus for entrapping food-particles. These particles are passed on to the peri-pharyngeal bands which, conduct them in turn into the dorsal groove.

The gill of Amphioxus functions mainly as a feeding organ and a water pump, and probably not at all as an organ for aerating the blood.

The mode of feeding in Ascidians is almost exactly the same as that described above for Amphioxus. Food-collection, however, in Ascidians is effected by cilia on the papillae and similar outgrowths on the gill, and is also helped in some forms by transverse waving of the longitudinal bars, by which process the food is pushed as well as lashed towards the dorsal region of the pharynx.

On October 28th, 1920, a conjoint meeting was held by representatives of the Development Commission, the Ministry of Agriculture and Fisheries and the Oyster Merchants and Planters Association to institute investigations into the cause of the abnormal mortality which had occurred among oysters in the oyster beds in the Thames Estuary during the summer of 1920. As a result of this meeting investigations were begun under the general direction of the writer. On the completion of the work a full report of the results obtained was forwarded to the Fisheries Department, Ministry of Agriculture and Fisheries. The more important parts of that report will be published as follows: Part I, Main Report, Fishery Investigations, Ministry of Agriculture and Fisheries, London, Series II, Vol. VI, No. 3, 1923; Part II. containing the more important Appendices, will appear later.

The hermit-crab, Eupagurus Bernhardus, is common in the oyster beds in the upper part of the Fal Estuary, and experiments indicate, while observations and experiments on the mode of feeding virtually prove, that these hermit-crabs do not harm healthy small oysters one inch or more in length, and the larger oysters, but that spat less than one inch may occasionally be damaged or eaten by hermit-crabs picking with their claws indiscriminately at growths on shells and stones.

E. Bernhardus obtains food largely by its small claw and third maxillipedes, and may at certain periods of the year feed mainly on microorganisms, and at others on macroscopic, but mainly tiny living organisms which have been disturbed and captured in the deposits on the sea-bottom. Food can be obtained by the use of the third maxillipedes alone.

Some preliminary observations in North Cornwall (Orton, 1946) showed that the periods of breeding of the three British species of limpets were different. In order to determine these differences more accurately, and to study the breeding cycle, samples of limpets from six localities in Britain were examined at regular intervals for 5 years. This paper gives the results obtained for the common limpet Patella vulgata, which was present at all the localities sampled and was the most intensively studied of the three species. Later papers will deal with the remaining species and with other aspects of the investigations.

The spatfall in 1924, as in 1923, was very slight and from the point of view of the oyster-producer was a failure, and was little better in 1922.

The growth of oysters in the summer of 1924 was unusually great; this has had the effect of bringing a large proportion of small oysters to a legally takeable size.

The dredging results have, therefore, been much better than they were expected to be in the season of 1924–25, but the effect has been to deplete the beds still more of reserve stocks of small.

Practically all the present stocks of small oysters are of a size between 2 and 2½ inches.

With only average growth in 1925 and 1926 a large majority of these small oysters will have attained a size which will not pass through a 2½-inch ring; hence the beds are in a dangerous state.

If, therefore, dredging continues under the present conditions, almost the whole of the present stock of small will have grown to large oysters and be cleared off the beds in the season of 1926–27.

It is shown that although oysters may grow to a size of 2½ inches at Falmouth in small numbers in three summers, yet four summers are required before a fair proportion of spat can be expected to attain a size of 2½ inches.