. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . oplast is of the typical Volvocine kind and contains a pyrenoid. Apigment-spot is present in some forms but absent in others. 1 Pascher has attempted to overcome this difficulty by splitting up the genera Ulothrix andStigeoclonium ( = Myxonema) on grounds which appear to be inadequate. Polybleph or /V 1(55 Multiplication takes place by longitudinal fission, in some forms com-mencing at the anterior and in others at the posterior extremity. Re
. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . oplast is of the typical Volvocine kind and contains a pyrenoid. Apigment-spot is present in some forms but absent in others. 1 Pascher has attempted to overcome this difficulty by splitting up the genera Ulothrix andStigeoclonium ( = Myxonema) on grounds which appear to be inadequate. Polybleph or /V 1(55 Multiplication takes place by longitudinal fission, in some forms com-mencing at the anterior and in others at the posterior extremity. Resting-cells are formed by the direct encystment of the motile individuals, Gametesof a more or less isogamous character occur in Dunaliella (Teodoresco, 05),and they fuse in pairs to form zygotes. The most primitive genus of the family is Polyblepharides, in which the body of thecell is conical with a broad anterior end to which are attached from six to eight cilia. InPyramimonas, which possesses only four cilia, the cell-body is also more or less conical, Chloraster, which is furnished with five cilia, is and is four-lobed in the anterior H Fig. 95. A—E, Dunaliella salina (Dunal) Teodoresco ; A and B, normal form of zoogouidia{ = vegetative cells) ; C and D, stages in division, in D the second cilium making itsappearance; E, single cell showing detailed structure. F—I, Pyramimonas delicatnlintGriffiths ; F, vegetative cell; G, beginning of longitudinal fission, the pyrenoid havingdivided and 8 cilia developed ; //, peculiar blistering and disintegration of cell on treatmentwith 4 per cent, formalin, showing swelling of cilia at their extremities; I, anterior axialview of H at an earlier stage in disintegration showing lobed chloroplast. c, cilia :H, nucleus; pc, posterior excavation of chloroplast; j)t, protoplasmic membrane; pi/,pyrenoid ; s, minute grains of starch; /, plasmatic thread from nucleus to base of — D, after Teodoresco, x 1000 ; E, aft
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