Observations on the Fine Structure of Zoids of the GenusPhaeocystis[Haptophyceae]

Observations on the fine structure of two clones of zoids derived fromPhaeocystis pouchetiis.l. are presented, with special reference to the scales, pyrenoids and haptonema, in which both clones agree. An unexplained difference between them in the form of a threadlike deposit external to the scales in one clone only is described in a preliminary way. The most remarkable feature encountered is the presence of some unexplained bulbous inclusions distorting the tip of the haptonema but perhaps also present in a less extreme form in other types recently examined alive. The interpretation of these findings is discussed.