Observations on the Fine Structure of the Pyramimonas Stage of Halosphaera and Preliminary Observations on Three Species of Pyramimonas

Abstract

The entire cell surface, including the flagellar surfaces, of three species of Pyramimonas and of two different strains of Pyramimonas-hke zooids of Halosphaera are shown to be covered with scales in at least two layers, namely, an underlayer of very small scales arranged directly on the flagella membrane or plasmalemma and one or more outer layers of much larger scales of different character. On one and the same cell the shapes of the scales of all layers are different on the flagella from those on the body. Among all the taxa studied the flagella scales are very similar but those of the bodies are specifically differentiated; details are illustrated in the plates. In two taxa {Halosphaera and Pyramimonas amylifera) the outer scales on the flagella have been shown to be consistently arranged in 9 longitudinal rows; numerical information is not available for the other taxa studied but they are not expected to be different. The presence of an unusual type of flagellar hair has also been noted though those have not yet been studied in detail.