. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . oduction takes place by comparatively small zoogonidia, which arebiciliated in Chwtomorpha and quadriciliated in Urospora. In the lattergenus they are also more elongated and seen from the front are four-angled;they are also capable of slight changes in external form. Large numbers ofzoogonidia are formed in each ccenocyte and are usually set free through alateral aperture formed by the dissolution of the wall at that point (fig. 170 4)- 266
. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . oduction takes place by comparatively small zoogonidia, which arebiciliated in Chwtomorpha and quadriciliated in Urospora. In the lattergenus they are also more elongated and seen from the front are four-angled;they are also capable of slight changes in external form. Large numbers ofzoogonidia are formed in each ccenocyte and are usually set free through alateral aperture formed by the dissolution of the wall at that point (fig. 170 4)- 266 Siph o i locladiales Asexual reproduction also takes place by means of thick-walled ccenocysts,formed from single segments which become free. These either germinatedirectly or produce numerous zoogonidia after a period of rest. Gametes alsooccur in both genera; in Chtetomorpha they are green and isogamous, but inUrospora they are anisogamous, the male gametes being smaller than thefemale and almost colourless. The zygote germinates only after a period ofrest. Zoogonidangia and gametangia may occur simultaneously in the samefilament (Borgesen, 02)..
Size: 1098px × 2275px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpublishercambridgeengtheuni
