Distribution of the Organ-Pipe Diatom (Bacillaria paradoxa)

Abstract

IN connexion with the interesting question raised by Mr. F. Chapman in NATURE of January 6, p. 15, as to the peculiar movements of Bacillaria paradoxa being due to osmotic pressure, I am writing to say that all the specimens observed by Mr. H. Weaver and myself that were gathered from the Staffordshire and Worcestershire Canal at Stourport and from ponds at Wilden and Hartlebury (see NATURE, vol. 108, p. 163) were very active and so continued during the period we kept them under observation (about a week in each case). The water in this canal and in these ponds is some eighty miles removed from the sea. It is quite fresh and not at all brackish.