. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . btusi-folius, Lychnis Flos-cuculi, etc.). Some species are marine, occurring in the Chlorochytriese 211 peripheral portions of the thalli of various larger marine Algte. Reproductiontakes place by the formation of zoogonidia or isoplanogametes, or contents of the cell become broken up by successive divisions, in amanner similar to that which occurs in Characium, into a large number ofsmall zoogonidia or gametes. These are liberated e
. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . btusi-folius, Lychnis Flos-cuculi, etc.). Some species are marine, occurring in the Chlorochytriese 211 peripheral portions of the thalli of various larger marine Algte. Reproductiontakes place by the formation of zoogonidia or isoplanogametes, or contents of the cell become broken up by successive divisions, in amanner similar to that which occurs in Characium, into a large number ofsmall zoogonidia or gametes. These are liberated either by a perforation inthe wall of the mother-cell or by the gelatinization of the inner layer of thewall, which then becomes protruded as a large vesicle in which the motilecells swarm for a short time. The biciliated zoogonidia or the quadriciliated zygozoospores come to rest on the epidermis of the host-plant and germinateat once. Should the new plant be an endophyte, it penetrates the host eitherthrough a stoma or by forcing itself between two epidermal cells. Some ofthe vegetative cells become akinetes and pass the winter in that Fig. 138. A, young vegetative cell of Chlorochytrium LeninsR Cohn, x 475. B—D, GentrosphseraFacciolse, Borzi; B and C, x 475 ; D, showing escape of zoogonidia (after Borzi), x 410. The cell-wall is invariably thick and strong in the adult cells of all themembers of this group. There is one extensive parietal chloroplast, usuallylining the whole of the cell-wall and often with inwardly extending lobes, andcontaining one or many pyrenoids. In Chlorococcum the cells, which live on damp ground or in water, aregregarious and often form a stratum. They grow much in size, becomecoenocytic, and often angular by compression. From 8 to 32 zoogonidia arisein each mother-cell. The species of this genus are for the most part veryimperfectly known. Centrosphtera is another gregarious form occurring as arule unattached among various Algae i
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