On the structure and movements of the latero-frontal cilia of the gills of mytilus

Abstract

The following observations were made at the suggestion of Mr. J. Gray, of King’s College, Cambridge. Their object was to investigate how far the structure and movements of these cilia, which have been used by him in experiments on the mechanism of ciliary behaviour, could be analysed by the use of the microdissection needle. The work was carried out on Mytilus gallo-provincialis in the Stazione Zoologica at Naples during the months of January and February, 1923. The arrangement of the various groups of cilia on the gills has been fully described by Orton (1912), and a summary of his observations is given by Gray (1920, 1922). A diagram of a cross-section of a gill-filament showing the arrangement of the cilia is given in fig. 1 (modified from Orton). The latero-frontal cilia form a single row on each side of the frontal face of the filament. The plane of their beat is transverse to the length of the gill-filament and the effective beat is towards the frontal face.