A contribution to our knowledge of Mallomonas.

Abstract

This paper gives general observations on four species of Mallomonas. The chromatophore is single in all, but deeply divided into two lobes. The bristles are always hinged and readily movable. The following new features are described: in M. leboimii, the cyst; in M. lychenensis, the shredding of the scales and growth of small individuals; in M. teilingii, the stages leading to cyst development and in M. intermedia var. gesticulans var. nov. the structure of the scale and various growth and reproductive stages. Two internal parasites, ? Protozoa, are described, one on M. teilingii and one on M. intermedia var. gesticulans. These are of importance in destroying a population and in forming cysts which have been mistaken for Mallomonas cysts, one forming the basis of a new species of Mallomonas. SUMMARY 1 Certain aspects of the ecology, structure and life history of four species of Mallomonas are described. 2 M. intermedia Kisselew var. gesiiculans var. nov. and the cyst of M. leboimii Bourrelly are described. 3 The chromatophore in all four species is single and deeply lobed. 4 Several stages of the life cycle of M. intermedia var. gesticulans and M. lychenensis Conrad are described (some of them seem to be new), and also cyst formation in M, teilingii Conrad. 5 The tripartite scale and bristle attachment, and also the movement of bristles, are described for M. intermedia var. gesticulans. 6 The scale arrangement is described for M. intermedia var. gesticulans and M. lychenensis Conrad, and the shedding of the scales for M. lychenensis. 7 Two internal parasites are described, one affecting M. intermedia var. gesticulans and one affecting M, teilingii.