The vertical migration of two Euglena species and several diatom species into and out of the sediment on the banks of the River Avon has been studied under natural conditions. All species have been shown to migrate vertically upwards when exposed during daylight. Tidal flooding of the sediment is generally preceded by re-burrowing of the algae beneath the surface. Methods have been devised to follow these migrations in both the field and laboratory. Laboratory experiments show that these migrations are rhythmic, continuing under constant illumination and temperature and removed from tidal influence. The effect of three different temperatures and three different light intensities has been investigated. Transfer from low to high temperatures has been shown to reset the phase of the rhythm. The results are discussed in relation to other work and to the ‘biological clock’ hypothesis.

Nautilus macromphalus Sowerby when freshly caught was close to neutral buoyancy having a weight in sea water of about 0–2% of its weight in air. The animals without their shells varied considerably in density but the volume of the shell was an approximately constant fraction of the total volume of the whole animal and whole animals were brought approximately to the same density by havingmore or less liquid inside the chambers of the shell. About 80 % of the gas space in the shell was used to support the weight of the shell itself in sea water.In an adult animal the centre of buoyancy was found to be about 6 mm above the centre of gravity, which made the animal very stable in its natural swimming position, a couple of about 350 g. cm being required to turn it through 90°. The pearly partsof the chamber walls were impermeable to sea water but the chalky and horny siphuncular tubes joining the septal necks were very porous. The most newly formed tenor so chambers were the only ones to contain liquids in appreciable volume and theydid this in diminishing amounts from the newest to the oldest. The watery liquids found within the chambers were always hypotonic to sea water and sometimes markedly so; they contained principally sodium and chloride ions. One animal was in the process of forming a new chamber, this incomplete chamber was completely full of liquidwith an osmolarity close to that of sea water but differing in composition from seawater.

The Council records with regret the deaths of Mr Morley H. Neale, C.B.E., Dr M. N.Hill, F.R.S., Prof. W. F. Whittard, F.R.S., and Prof. Hans Pettersson, For.Mem.R.S. Mr Morley Neale had been a member of Council on a number of occasions, a Vice-President of the Association since 1951, and by a gift made in 1958, he founded the Morley Neale Fund for 'the benefit or pleasure of the Plymouth Laboratory staff and ship's crews'. Dr Maurice Hill had for many years been associated with the life and work of the Laboratory and its ships. He first served on the Council in 1956 and was a member at the time of his death. Prof. Whittard had served on Council for two periods and in recent years had made a number of cruises in 'Sarsia' in the course of his investigations of the geology of the sea floor in the western English Channel. Prof. Hans Pettersson was elected an Honorary Member of the Association in 1949 and was at the time of his death second in seniority of the nine Honorary Members.