The Size of Diatoms. I. The Diameter Variation of Rhizosolenia Styliformis Brightw. and R. Alata Brightw. in Particular and of Pelagic Marine Diatoms in General

Abstract

1. The diameters of samples of Rhizosolenia stylijormis taken in the S. W. North Sea between 1932 and 1934 revealed the presence of large and small populations. The largest diatoms were found in 1933, in which year, or late in 1932, it was thought that auxospore formation might have taken place.2. The large and small groups mentioned in (1) gave indications of a continuous diminution of size judging by an inspection of their modes. Notwithstanding this there appears to have been some selection of the larger cells, as the whole samples tended to increase in size with a rise of temperature.3. The correlation coefficient between the temperature at 20m. and the mean diameters was 0-59. That for salinity in the same circumstances was 0-59. The inverse correlation with salinity is thought to be due to the topography of the area.