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DURING the cruise of M.V. Magga Dan under charter to the Antarctic Division of the Australia Department of External Affairs during January-April, 1959, phytoplankton samples were collected by a modified Hardy Indicator, and later examined at the Commonwealth Scientific and Industrial Research Organization's Division of Fisheries and Oceanography, Cronulla. In the course of this examination, a peculiar diatom was observed on two occasions in the same sample. In each case, one valve of a cell had the characters of Coscinodiscus, the arrangement of the areolae resembling that of C. lineatus; but the valve was deeply concave. The other valve was characteristic of Asteromphalus roperianus. In one example two cells were in contact, one having the mixed character described, the other being a typical Coscinodiscus, with both valves identical. The other example was solitary, and smaller (65µ compared with 100µ), showing that it belonged to another generation.

MARINE biologists have been slow to recognize that the smaller phytoplankton elements which will pass through the finest nets are of great importance in the productivity of the oceans. In order to get some quantitative data on this subject for eastern Australia (lat. 33–34° S.), we have recently conducted experiments in which 44 gallons of sea-water were pumped into a drum and filtered through a phytoplankton net having 170 meshes per inch. The filtrate was collected and the particulate matter was spun out of 2-litre aliquots using a continuous centrifuge running at 13,000 rev./min. and having a slightly coned cup of maximum internal diameter 4.5 cm. and height 3.8 cm.

DURING a study of the reduction of sulphates in Zostera mud flats, it was found that when autoclaved Zostera was added to autoclaved sand and sea water, ferrous sulphide was rapidly produced. At first it was thought that this reduction was microbiological, but later it was found that living Zostera could bring about the reduction. A study of Zostera showed that a lead mirror could be produced from lead acetate by heating this substance with Zostera leaves and that this mirror was intracellular in the leaf parenchyma. When washed Zostera leaves are heated with distilled water, cadmium acetate papers show yellow cadmium sulphide, and, at times, metallic cadmium. If the distillation is carried out under nitrogen, the steam distillate condensed into 100 ml. of N/1,000 hydrochloric acid at pH 3.35 yields a nitrogenous solution containing up to 6.75 mgm. nitrogen per litre, and the pH rises to 7.0 with a volume increase to 450 ml. In addition, there is a volatile sulphur-containing substance which is soluble in alcohol and produces lead sulphide from lead acetate. This sulphur compound gives no precipitate with mercuric chloride and a white precipitate with alcoholic lead acetate, suggesting a thioether. It has an unpleasant odour. The production of lead sulphide from lead acetate seems to depend on a partial volatilization of the nitrogenous base. Posidonia appears to contain a different sulphur derivative with a more pungent odour.