Abstract
The cytochemical reactions of the attachment mucilage of 12 diatom genera (total 17 species) have been examined. These organisms are all found as members of fouling communities and, in some cases, are the dominant component. In every case the mucilages were found to be exclusively polysaccharide, except in Berkeleya rutilans where a low level of protein was also detected. All the polysaccharides contained anionic constituents, with carboxyl groups predominant in the pad-forming species and in early stages of attachment of the stalked species, whilst sulphated polysaccharides were more prevalent and in greater proportions in chain-forming and tube-dwelling species and in the stalks of Achnanthes and Licmophora. These stalks show distinct anatomical differences as well as differences in cytochemistry. The possible significance of the variations in cytochemistry are considered for the different growth forms.