Monthly samples of the common British Laminariaceae and Fucaceae taken during 1946 have been analysed for cellulose.

The cellulose content has been found to increase with the depth of immersion of the weed.

In the Laminariaceae, both in the stipe and frond it undergoes marked seasonal variation, exhibiting two maxima, March/April and September/October with a distinct minimum in June/July.

In Laminaria cloustoni, in March, maxima of 5·7 (dry basis) occur in the fronds and 10·3% in the stipes with minima, in June, of 4·1 and 8·4% respectively. In Laminaria saccharina the cellulose content (dry basis) varies between 4–5% in the frond and 7–8% in the stipe and in Laminaria digitata between 3–5% in the frond and 6–8% in the stipe.

Sea water collected at Station E1, surface, between June 1948, and November 1949, contained suspended matter from 2·77 to 0·45 g./m.3 (or parts per million) dried and ignited. A few determinations of insoluble organic matter gave 1·77 to 1·15 parts per million dry weight at 100° C. The ignited residue contained from 55 to 17% silica, 28 to 3 of ferric oxide, 20 to under 1 of alumina and 70 (or excluding one high value 29) to 9 calcium carbonate. There was nothing in the records for temperature or salinity to suggest that the water mass had changed during the period of sampling.

The analyses reveal an unsuspectedly large amount of iron, compared with that found in solution. The ignited residue is rich in silicate, judging from the silica alumina ratio, but it is quite doubtful whether the additional supply of silicate available for diatoms is at all adequate to balance their requirements calculated on a phosphate utilization basis. It seems more probable that a considerable amount of the phosphate is available for non-siliceous phytoplankton.

The variability in catch of a series of hauls with a V.D. trawl taken under, as far as possible, controlled working conditions has been determined.

For analysis the species were divided into ‘round’ fish and ‘flat’ fish together with Nephrops; for both groups the coefficient of variation varied from 40 to 85 %. Taking 75 % as a representative value, the 2σ fiducial limits are 30–300 % for a single species from a single haul of half an hour duration.

It has been found that the standard deviation is roughly proportional to the mean, and that the variance is greater than the mean and increases with the mean. This suggests aggregation of the population.

The species are considered over the whole sampling period (4 weeks). Except for haddocks and dogfish the ‘round’ fish constituted a constant population. Changes were found in the other groups and their origin is discussed.

In the summer of 1949 a compound ascidian was collected from the shore of Seil Island, Argyll. This proved to be a new species of the family Didemnidae. It is proposed to name it Lissoclinum argyllense, the specific name indicating the area in which it was first found. No species of Lissoclinum has hitherto been included in the British fauna.

Determinations of total phosphorus in water samples have shown areas in the western English Channel with water containing as little as 10 mg. P/m.3, and other areas with double, and more than double, this concentration.

The integral mean concentration of total P in the water column, 20 miles off-shore from Plymouth, has fluctuated between 10 and 16 mg. P/m.3 since June 1947.

The changes which have taken place in this integral mean concentration are attributed to different water masses, of different total phosphorus concentration, passing through the area, rather than to a seasonal change in the total phosphorus content of a water mass. No marked deposition of phosphorus-containing detritus could be found.

Changes in this integral mean were not coincident with changes in salinity. The geographical distribution of total phosphorus does not coincide with the geographical distribution of salinity.

Simple methods for recording the water currents, which many polychaetes drive through their tubes, are described. The circulation may be either open (the worm having access to large amounts of well-aerated sea water) or closed (in which case the worm can circulate a small volume only, and there is no oxygenacion or removal of excretory products).

When on open circulation, both Chaetopterus variopedatus and Nereis diversicolor often trace quite regularly cyclical patterns for hours at a stretch. Each species has several possible patterns, and may change from one to another without evident external cause. The tracings of each species differ from those of the other, and also from those of Arenicola marina, which were described elsewhere.

The life histories of the small planktonic copepods of Plymouth were studied during 1947. The samples were taken at Station L4 with Harvey measuring nets, and are thus truly quantitative.

The main species concerned were Pseudocalanus elongatus, Paracalanus parvus, Centropages typtcus, Temora longicornis, Acartia clausi, Oithona similis, O. nana, Oncaea venusta and Corycaeus anglicus.

The species common in summer—all but the last three of the above—behaved in a very similar way, producing probably five generations in the course of the year, but differing from each other in the relative and absolute abundance of the different stages at different times of the year.

The respiratory rates of four species of planktonic copepods were measured. In two of the species measurements were made with two copepodite stages, and with adult male and female specimens.

The rate for Calanus finmarchicus Stage V at 17°C. was found to be 0·52 μl./cop./hr., a figure which agreed with previous measurements.

For all the species and stages studied the respiratory rate was found to be closely proportional to the length to the power of 2·2.

The relevance of such measurements to conditions in the sea is briefly discussed.

A certain variation in level of the fucoid zone with latitude is demonstrated. The belt of Fucus vesiculosus and F. serratus lies lower on the Devon coast than on either the Manx or the Argyll coast.

The conditions for the optimum germination of fertilized eggs are dissimilar to those for maximum rate of frond-extension.

Normal growth-rates have been established for both species for the first 3 years of life. In F. vesiculosus the average rate of elongation per week is 0·48 cm. on the Devon coast, 0·45 cm. on the Manx coast and 0·68 cm. on the Argyll coast. In F. serratus the average rate of elongation per week is 0·49 cm. on the Devon coast, 0·68 cm. on the Manx coast and 0·85 cm. on the Argyll coast. The rate of growth is shown to vary with the conditions of the environment. Shelter from rough water tends to enhance growth-rate, and there is an indication that greater stature is achieved by the plants from the Argyll station than from either of the other stations.

An account is given of the bottom-fauna of Great West Bay from samples taken in 1948 with a new sampler. Comparison is made with a similar survey made by Mr E. Ford with the Petersen grab in 1923.

The deposits contain a fair proportion of mud, and the ‘EcVg’ communities denned by Ford dominate the area. Within the Bay are found fairly dense beds of Turritella communis, Lutraria sp., Callianassa subterranea and Spisula solida.

No marked changes in the fauna seem to have occurred since the earner survey. The fauna is briefly compared with that of the Plymouth area.

The volumetric and qualitative analysis of the food of Gadus minutus has been discussed. The post-larvae feed entirely on copepods, mostly Pseudocalanus elongatus. The O-group feeds on copepods, small decapods, amphipods, polychaetes and isopods. The adolescent and adult groups feed on larger decapods like Processa canaliculata, Galathea spp. and Portunus spp., fish, polychaetes and amphipods.

The age and rate of growth of G. minutus have been computed from a study of the supra-occipital crest. These age determinations have been correlated with the age determined by scales, otoliths and size-analysis. Back-calculations have been made by graphical method and by using the Lea-Dahl formula. The differences between the back-calculated lengths and actual observed lengths are negligible.

The filtering rate of four species of marine planktonic copepods was measured by estimating the rate at which they consumed cultures of Chlamydomonas.

The filtering rate was independent of the concentration of the food organism and it is concluded that the copepods were acting as filter feeders.

The filtering rates were much greater than those reported by Fuller & Clarke (1936) and Fuller (1937), but agreed with those reported by Harvey (1937).

Some evidence was obtained that grazing was restricted to some only of the 24 hr., most probably to the hours of darkness.

The filtering rates were approximately proportional to the square of the linear dimensions of the copepod.

The purely mechanical selection suggested by Fuller (1937) to account for differences in filtering rates obtained with different species of diatoms cannot account for all the differences which have been observed.

It is probable that the copepods could obtain sufficient particulate food in the sea by filtering a daily volume of water corresponding to the filtering rates found.

A study has been made of the food, population, and some aspects of the ecology of the common seal (Phoca vitulina L.) along the East Anglian coast.

Examination of stomach contents of 194 seals killed in the Wash in 1947 confirms earlier evidence that the species here feeds largely on whelks (Buccinum undatum). The food is estimated by weight as 92 % molluscs, 4 % fish and 4 % Crustacea. Young seals for 2–3 months after weaning feed almost exclusively on shrimps (Crangon vulgaris).

Data derived from six stomachs, together with verbal reports, suggest that seals on the open coast feed more exclusively on fish, chiefly pleuronectids. This agrees with the findings of other workers in Holland and Washington State, U.S.A., that fish are the primary food animals. It is therefore suggested that in the Wash, where suitable breeding sands are common, the seals have become adapted to feeding on a ‘second-class’ food in the absence of dense stocks of fish.

The last 20 years have seen many advances in our knowledge of the mechanisms responsible for the transmission of impulses in peripheral nerve fibres. This has come about largely through researches on the nerves of marine invertebrates. Much of the work has been done at Plymouth. The purpose of this article is to give some of the reasons why certain features of these nerves, which distinguish them from the nerves of vertebrates, should make them so desirable for experimental work.

The production of chemicals from the brown seaweeds is one of the oldest branches of the chemical industry, having its origin as far back as 1720 when soda was first produced from kelp in France, and soon after taken up in Ireland, Scotland and Norway. Until the early nineteenth century this was the only source of this chemical on which the glass and soap industries were built up. When the cheap Leblanc soda later became competitive the industry was able ot switch to potash and iodine production, a demand for which had arisen about the same time. This industry reached sizeable proportion, as is evidenced by the fact that in 1820 more than 20,000 tons of kelp were produced in the Outer Hebrides, involving the collecting and burning of about a million tons of cast weed.

The marine Amphipoda of the Plymouth area, as a group, were last given attention in the middle 1930's by Crawford (1936,1937). Renewed investigation after the lapse of 15 years has indicated that knowledge of species present was by no means complete, or that some changes have occurred in the interval, or both. In a recent survey of the amphipod fauna of the Isle of Man, Jones (1948) found no indication of the existence of undescribed species, nor even of known species previously unrecorded from Britain. The experience at Plymouth has been quite the reverse.