Movements and Co-ordination of the Latero-frontal Cilia of the Gill Filaments of Mytilus

Abstract

THE observations described here were made on very young mussels (Mytilus edulis) in which the valves are sufficiently transparent to allow direct observation of the gill cilia in the intact animal. In young animals, the structure of the gill filaments and their ciliature is essentially similar to that of adult mussels; some evidence was obtained that the same holds for the movements of the cilia. Our observations concerned the latero-frontal cilia, which are responsible for the filtration of suspended food particles from the sea water. With this material the frontal gill surface may be viewed. The latero-frontal cilia move to and from the observer and, consequently, are only momentarily in focus. This disadvantage was overcome by the use of Gregory's solid image microscope¹, which offers a greatly increased depth of focus when compared with the conventional microscope. With this instrument it was possible to observe the entire latero-frontal cilium during all stages of its beat.