1. J. H. J. Poole’s neon lamp method (1928) of integrating the photo-electric current is serviceable for work at sea down to moderate depths, which further experience may extend considerably. It is specially valuable for determining the light just above the water, and at such depths down to 5 m., at which the variability of the light renders the potentiometer method (1925) very difficult or quite impossible in rough water. For greater depths, down to 70 m. (bottom in the English Channel around our normal range) we have so far been able to use the latter only.

2. The loss due to the shadow of the ship, obtained by subtracting the illumination just above water from that on the deck-house roof, was found to vary from an extreme case of 52 per cent, and a normal loss of 30 per cent, with an overcast sky, down to 11 per cent with a clear sun at 31° altitude.

3. The loss of light due to its entering the water was found to vary from 7·5 to 16·5 per cent, mean 13·1 per cent.

4. It is desirable that the illumination just above and just below the water surface should be determined by the neon lamp method as a routine.

In the course of a study involving the routine identification of Tunicata the need became apparent of an attempt being made to define more clearly than has been done the diagnostic characters of certain species. The examination of a widely-collected material demonstrates the fact that in certain species considerable variations in structure accompany changes of habitat (depth, latitude, temperature, type of substratum, etc.), while other species vary but slightly.

1. The observations were made on the Hunterston Sands, Ayrshire, opposite the Cumbrae.

2. Small cockles appear on the ground about the beginning of August. This points to the breeding season being in summer and not spring, as is usually stated.

3. By the end of the first autumn some few of the spat are as much as 10 mm. in length, but most are under 6 mm. The winter ring is faint and easily overlooked.

4. The first of the several well-defined rings is therefore not the first but the second winter ring.

The object of this short paper is to describe a number of fishes exhibiting interesting abnormalities. It will be seen from the list given below that several of the specimens to be described were sent to the Laboratory on the personal initiative of gentlemen to whom I express my thanks. I am also greatly indebted to Dr. H. A. Harris and the staff of the X-ray Department of the Institute of Anatomy, University College, London, for the beautiful radiograms they supplied.

During the year 1928 the writer was engaged in a study of the bionomics of the oyster drills on the oyster beds in the region of the River Blackwater, Essex. At this time the presence of a foreign species was detected (1) and definite records were made of the relative abundance of the three following drills or tingles:—Murex erinaceus (=Ocinebra), Purpura lapillus (=Nucella), and Urosalpinx cinerea. It so happened that the winter of 1928–29 was unusually cold; the temperature of the water over the oyster beds was unusually low in January and February, 1929, ranging about the freezing-point of fresh water (see Table II and Fig. 1). The oyster-cultivators in this locality had many years previously stated that during severe winters many marine animals, such as the oyster drills or tingles and the burr Echinus miliaris, are killed in such great numbers as sometimes to exterminate the species. The observations made by the writer in 1928 offered an opportunity to test these statements, and of estimating the effect of the extreme cold in early 1929 on the animals mentioned above.

The effect of light upon plant growth is a problem which has attracted many workers since the discovery of Priestly, in 1771, that a plant could purify fixed air, carbon dioxide, which was followed by the supplementary work of Ingen-Housz and Senebier, who showed that the phenomenon was associated with the nourishment of the plant, and took place only in sunlight and through the agency of the green portions of the plant.

Illustrations are given of successive stages of the gonadial products, of the European oyster (O. edulis) after the act of egg-spawning. Both, microscopic and fresh preparations are figured.

1. Ligia is a nocturnal animal inhabiting crevices in rocks above high-tide level. It is omnivorous though Fucus spp. form the main article of diet.

2. Immersion experiments were carried out in which the animals were subjected to a gradual transition from salt to fresh water. None survived this treatment for more than one month. It was noticed that the reduction in salinity was accompanied by an increase in the rate of beat of the pleopods.

3. Animals were subjected to sudden and gradual changes in temperature. One specimen survived a change from water at 15° C. to water at 30° C. for 28 minutes, but was dead after 78 minutes; a second, changed from water at 15° C. to water at 35° C, was to all appearances dead after 8 minutes, but recovered after being replaced in water at the original temperature.

1. The observed “action at a distance” undoubtedly exists.

2. This action cannot be ascribed to a radiation, nor more generally to an action “through the wall” of the receptacles.

3. This action must then be exercised “across the surface” of the wall of the receptacles by a mechanism which remains to be explained. This seems, however, to be of great interest in view of the apparently very small mass of the substance concerned in the action.

4. The action of something material is rendered probable from the fact that the eggs develop very abnormally in sea-water previously exposed to the active culture.

5. Although these experiments have only been carried out upon sea-urchin eggs, their conclusions may be valid in the case of the very numerous experiments concerning mitogenetic radiation.

1. Fat occurs in all three types of cell composing the gastric epithelium at the end of a period of fasting extending over 6 or 7 days, but is completely absent from the mucosa of all post-pyloric regions of the alimentary tract at such a time.

2. There is a marked increase in the fat content of the superficial epithelium of the stomach after 30 hours and 50 hours of gastric digestion, the stomach being thus shown to be an effective organ of fat absorption.

3. Considerable quantities of fat are present in the duodenal and intestinal epithelia after fat-containing meals have been digested. The rectum is capable of some slight absorption, although its capacity in this respect is very much smaller than that of the duodenum or intestine.

4. It is suggested that there is a transference of the function of fat absorption from the stomach to the post-pyloric intestine when the frequency with which meals are taken is increased.

5. Globules of true fat are not typically observed in the areolar tissue layer of the alimentary tract, although lipoid granules may occur in abundance. It is suggested that resynthesis of the cleavage products of fats does not occur in this layer.

6. Data are presented bearing upon the rate of digestion of Mytilus edulis and Nereid worm.

A Preliminary survey of the area with regard to the distribution of the total nitrogen and phosphate content of the muds was described in a previous paper (Moore, 5). A number of stations were worked, and these were further examined for nature and distribution of particles, water content, and density, and as a result of this survey certain stations were chosen as suitable for more extensive work. At the same time it became evident that the layers in which the greatest and most important changes were taking place were those within a few centimetres of the surface, and these were therefore studied most intensively.

1. Ligia is an omnivore, though normally feeding on Fucus. Portions of food are cut off by the mandibles and passed into the œsophagus. Its feeding period is limited.

2. The foregut is provided with a number of ampullæ and lamellæ which are furnished with spines and bristles and are so arranged as to form a filter for the separation of the liquid portion of the food from the solid particles.

3. A second filter is found in the floor of the foregut protecting the entrance to the hepato-pancreas.

4. A ventral valve is present preventing the entry into the hepato-pancreas of solid food from the intestine.

5. The hepato-pancreas consists of three pairs of tubules provided with a muscular network for producing contractions. The epithelium possesses discrete cells.

In fine muds such as those covering most of the bottom in the deeper parts of the Clyde Sea Area the formation of fæcal pellets is a factor of great biological importance. In these muds up to 40 per cent of the fine material is often consolidated into fæcal masses, and in extreme cases even the whole of the mud may be in the form of pellets. The significance of this process is clear. In the first place, the effective particle size of a large proportion of the mud is very greatly increased, and this in turn affects such characters as the porosity of the bottom, and the liability of the material to be transported by currents. In the second place, among selective feeders such as Syndosmya alba, which feed on the mud, there is an economy of labour, in that food which has once passed through the gut is set aside in a form in which it will be refused if again taken in by the siphons. This latter process can readily be seen in the example cited whose rejecta on examination prove to be almost entirely composed of pellets of its own and other species.

A study of the respiration and of the function of hæmoglobin in Planorbis corneus and Arenicola marina has been undertaken.

The oxygen consumption of Planorbis is of the order of 0·026 c.c. per gm. per hour, measured at 15° C.

The blood volume is approximately 0·581 c.c. per gm.

The combined oxygen of the blood is 0·013 c.c. per c.c. of blood, the total oxygen being 0·014 c.c. per c.c. The total oxygen capacity of the blood per gm. of snail is estimated to be 0·0081 c.c.

The oxygen supplied by the blood is calculated to last 18 minutes and is found by experiment to last 25 minutes.

The snail does not immediately oxidise its hæmoglobin after subjection to anaerobiosis. Oxidation begins after 10 minutes and is complete within 20 minutes.

The experiments to be described below were proposed by the Ministry of Agriculture and Fisheries and were carried out under the auspices of the Marine Biological Association, being subject to the direction of Dr. E. J. Allen, F.R.S., and Dr. E. S. Russell. Mr. Harvey, hydrographer to the Association, directed the construction of the sea-water pond and the fish boxes during the early stages of the preliminary work and assisted in organising supplies whenever alterations were made to the apparatus.

1. The yellow colours of the hydroids include at least two groups, the carotinoids found in the Antennulariidæ and Haliciidæ and the flavone-like pigments that occur in the Sertulariidæ. From the literature a third group, the uradines, may be added.

2. The flavone pigments and their relatives are all water soluble and are thus distinguished from the carotinoids which are not water soluble, but may be dissolved in the usual fat solvents.

3. In the Sertulariidæ studied, a graded series of chromatophore groups and pigments was found which ranged from the colourless species Sertularia argentea Ellis and Solander, through the yellow of Sertularella gayi Lamaroux and S. polyzonias Linnæus, to the orange-brown of Thuiaria articulata Pallas. The brown of Sertularia pumila is probably also a flavone derivative.

4. The flavones and related pigments occur extensively in the plant kingdom. It is probable that the flavone-like pigments found in the Sertulariidæ are of plant origin.

In the Plymouth district there are five or six species belonging to the Galatheidse, one Munida, and four or five Galathea. The species occurring are the following :—

Munida banffica (Pennant).

Galathea strigosa L.

Galathea dispersa Kinahan.

Galathea nexa Embledon.

Galathea squamifera Leach.

Galathea intermedia Lilljeborg.

In carrying out detailed investigations into the life-histories and distribution of the Rays and Skates around the extreme south-west of England, large numbers of commercial landings have had to be examined. On account of their size and cost, regular and adequate samples of Rays and Skates cannot be delivered at the laboratory, as is possible with such a small and inexpensive fish as the Herring, for example. It therefore has been essential to learn rapidly to distinguish the different species as they lie exposed for sale on the fishmarkets. This has been necessary not only to promote rapidity of work, but also to obviate all unnecessary handling of the fish, too much interference with which is apt greatly to annoy fishermen, salesmen, and buyers alike.

1. The bacterial content of mud deposits in the Clyde Sea Area has been investigated.

2. The number of bacteria is found to decrease from the surface downwards.

3. The numbers fluctuate very much in the top mud layers, and there is some evidence of bacterial zonation.

4. In the deeper mud layers the bacterial content for any given station is fairly constant.

5. The predominant organisms were found to be water bacteria of the Achromobacter and Chromobacterium type, and large spore-forming bacilli similar to common soil bacteria.

6. The factors affecting the bacterial content of the muds are discussed.

1. In a large number of experiments with Gammarus chevreuxi when the animals were kept under similar conditions at temperatures ranging from 20° to 28° C., twenty instances occurred in which red-eyed mutations appeared independently and simultaneously. The most important of these (Mutant Stock V) is described in detail in this paper.

2. The Red eyes which have arisen in this Stock V and in the four previous Stocks, I to IV, have proved to be all genetically distinct from one another.

3. There are at leadt two different classes of “red-eye,” the one simple, the other with intermediate stages. Mutant Stock V, here described, represents the second type. Differences in the method of origin of the two classes have been pointed out.

4. The inheritance of the red-eyedness of the second class—namely, that in which intermediate stages and various colour changes occur—is of a complicated kind. For an interpretation in terms of Mendelian genes, even if allowance is made for an extent of variation in members of one particular genotype, clearly several of them are involved. Further, there must be considerable interplay of one kind or another among the different genes.

5. Although so many different colour shades have appeared in Mutant Stock V, all can be interpreted in terms of varying concentrations of two pigments—the black and the red. Dilute black pigment with little or no red gives a purple eye.