It has been well established that some of the features of the feeding and digestive process in molluscs are rhythmic in character. Notably Hirsch (1915, 1917, 1931) has demonstrated a rhythmic periodicity of secretion in the salivary glands and digestive glands of some carnivorous Gastropoda, and Krijgsman (1925, 1928) has done similar work on the land pulmonate Helix. In all of these animals—and in cephalopods, too, where there is a more elaborate nervous control of secretion—discontinuous feeding is the rule. In the other and perhaps larger category of molluscs—those continuously feeding on fine particles—the central mechanism of the gut is the crystalline style, or its forerunner the protostyle. Here the need is, in Yonge's words (1937), ‘to the extent to which they depend on extracellular enzymes for digestion, continuous secretion’. In Yonge's view, now classical, the style was regarded as ‘an ideal mechanism for the continuous liberation of small quantities of an amylolytic enzyme’. Graham (1939), in his work on style-bearing gastropods, showed that the style is in general confined to animals with a continuous feeding habit, whether by ciliary means or by using the radula to graze on and rasp off fine particles. It is known that style secretion stops and the style is frequentiy dissolved when animals are removed from the water and cease feeding (see Yonge, 1925).

It is well known that towards the limits of an animal's geographical range both its abundance and exact boundaries may fluctuate from time to time. These fluctuations can sometimes be correlated with environmental changes, and thus may help to assess the relative importance of the factors that control distribution. For example the distribution of the common intertidal barnacles Chthamalus stellatus (Poli) and Balanus balanoides (Linnaeus) underwent changes which were attributed to a general rise in temperature over several years (Southward & Crisp, 1954a). The abundance of these barnacles has fluctuated further since 1951–52, and we are now able to analyse more closely the relation between the population changes and environmental variations.

A number of records from echo-sounders have been loosely attributed to the presence of plankton. Only two records have been adequately identified as having been produced by plankton; first, the traces offish larvae, or shallow scattering layers (Burd & Lee, 1951); and secondly, the echo layer, at the depth of the temperature discontinuity or thermocline, which is sometimes associated with plankton animals or plants (Cushing, Lee & Richardson, in press). A third type of record, that from the ‘deep scattering layer', has been associated with the presence of euphausiids (Hersey & Moore, 1948; Moore, 1950; Boden, 1950): an equally plausible association with the presence of fish has been made by Marshall (1951), Tucker (1951) and Hersey & Backus (1954). A fourth type of echo record, a ‘noisy’ record, will be described and will show that it is probably attributable to plankton organisms, consisting, in one instance, of euphausiids.

Little is known about the food of the nauplii and early copepodite stages of copepods, although it has usually been assumed that the food particles must be smaller and perhaps more concentrated than for adults. A few observations have been made on the feeding of the young stages of Calanus in the laboratory, but none are available on feeding under natural conditions. It has been suggested (Marshall, Nicholls & Orr, 1934) that the success or failure of a brood of Calanus in the sea might depend on the presence of a rich food supply during its development. Experiments were therefore undertaken to find what organisms could be ingested by the nauplii and early copepodite stages, how much of the different foods could be digested, and how much water they could filter in a day.

In October 1921, a specimen of an echiuroid was taken in the otter trawl of the S.S. Salpa, in the neighbourhood of the Eddystone lighthouse. The specimen, a female, was provisionally identified by Mr E. Ford as Hamingia arctica Kör & Dan. The pharynx and uteri were opened in an unsuccessful search for males, after which the specimen was preserved in alcohol and put in the museum at the Plymouth Laboratory. In the following month, two more specimens were taken in the dredge by Dr R. S. Clark, a few miles from the same locality, and placed in the museum without further examination. No more specimens were obtained until April 1925, when one was taken in a trawl offRame Head, near the entrance to Plymouth Harbour. This specimen was examined by O. D. Hunt, and was found to be a female with uteri containing ripe eggs. Twenty-eight males of minute size were discovered attached externally to the female in a groove in the skin which extended for a short distance in the median line just posterior to what appeared to be a single genital orifice.

Lasaea rubra is the smallest and commonest of Plymouth bivalves. It is intertidal on rocky shores, often in immense numbers, in crevices and other protected places, and in Pygmaea pumila (Colman, 1940). This bivalve is an excellent laboratory animal. It remains fully active for several days under laboratory conditions, and a large number of animals can be used in a single experiment, eliminating the variations in activity found when dealing with a few, or single specimens of larger animals. Because of the relatively high position Lasaea rubra may occupy on the shore its feeding cycle is broken by regular dry periods at each tide. Thus, for experiments relating to periodicity in feeding, we have an animal whose times of feeding can easily be ascertained and experimentally varied over a wide range. Lastly, in making serial sections and in examining total gut contents, in work on the digestive system, the small size of the animal is of obvious advantage.

Fish eggs can be divided into three main groups: marine pelagic eggs which float of their own accord, marine demersal, and freshwater demersal eggs. The embryological development of freshwater teleosts follows an accepted pattern, demonstrated by morphologists during the nineteenth century. Marine embryos, both pelagic and demersal, do not conform in all respects to this pattern, and misunderstandings have frequently arisen by lack of attention to known structural differences between the three groups. Mclntosh & Prince (1890), in their comprehensive review offish development, emphasized some outstanding anomalies in pelagic structure, but gave no adequate explanation of their occurrence.

The presence in the sea of vitamin B12, or of its analogues, has been found necessary for the growth of several species of unicellular plants (e.g. Provasoli & Pintner, 1953; Droop, 1954, 1955).

Bioassays of the quantities in inshore waters during winter have been made by Lewin (1954) and by Droop (1954). The present investigation, carried out in 1955, was designed to extend this study and compare different seasons of the year.

The final regeneration stages of the nitrogen cycle in the sea are believed to consist of the bacterial oxidation of ammonium-nitrogen to nitrite and finally nitrate-nitrogen. There have been many attempts to demonstrate the presence in the sea of marine counterparts to the terrestrial Nitrosomonas and Nttrobacter. (See Zobell, 1946, for bibliography of the earlier work.) Bacteria which can oxidize either ammonia or nitrite are easily demonstrated in samples of bottom material or water contaminated by land drainage or bottom deposits. On the other hand, there has been general failure to demonstrate the presence of such species in the upper layers of the open ocean.

Isolated individuals of certain species of cirripedes are known to remain unfertilized at the time when the majority of contiguous individuals are carrying egg masses. From a very large number of observations on both Balanus balanoides (L.) and Elminius modestus Darwin (Crisp, 1950, 1956) there remains little doubt that in these two species copulation is necessary before eggs are brought into the mantle cavity where they are fertilized. Though fewer field observations have been made, Balanus crenatus Bruguière appears to behave similarly, isolated specimens grown on raft-exposed panels never bearing fertilized egg masses (Crisp, 1950; Barnes, unpublished observation). B. balanus (L.) (= B. porcatus da Costa) is also in all probability an obligatory cross-fertilizing hermaphrodite, though the available evidence does not exclude the possibility of self-fertilization in rare instances (Crisp, 1954; Barnes & Barnes, 1954).

The Council have great pleasure in reporting that Prof. A. V. Hill, C.H., O.B.E., F.R.S., was elected President of the Association in June in place of Prof. Sir James Gray, Kt., C.B.E., M.C., F.R.S., who had served for the preceding ten years.

The Council wish to record their deep appreciation of the many services rendered to the Association by Sir James Gray during his long term of office as President, and are glad to report that he will continue to serve on the Council as Governor representing the Royal Society. Sir James Gray has been elected a Vice-President of the Association.