. Botany for high schools. Botany. FILAMENTOUS GREEN ALGM 221 which lash about and cause the plant to swim rapidly around in the water. In the swimming stage the plant is green, the chloro- phyll usually not being obscured by the red pigment. As the small pools dry out the swimming plant passes again into the resting stage and acquires the red pigment. SG2. Single-celled green algae in colonies.—The single- celled algae just described lead an independent or individual existence. There are others in which the individuals are asso- ciated in definite colonies. Some of these are motile during the
. Botany for high schools. Botany. FILAMENTOUS GREEN ALGM 221 which lash about and cause the plant to swim rapidly around in the water. In the swimming stage the plant is green, the chloro- phyll usually not being obscured by the red pigment. As the small pools dry out the swimming plant passes again into the resting stage and acquires the red pigment. SG2. Single-celled green algae in colonies.—The single- celled algae just described lead an independent or individual existence. There are others in which the individuals are asso- ciated in definite colonies. Some of these are motile during their vegetative existence as in Pan- dorina moriim. This is a colony of sixteen like individuals ar- ranged in the form of a sphere enclosed in a thin gelatinous sheath, each oval individual with a pair of cilia projecting beyond the sheath. The vibra- tion of the cilia causes a rapid rotary motion of the sphere. The colony multiplies by each in- dividual dividing into sixteen small individuals. The small. Fig. 175- Pandorina morum (Miill.) Bor}'. I, motile colony; II, colony divided into i6 daughter colonies; III, sexual colony, gametes escap- ing; IV, V, conjugating gametes; VI, VII, young and old zygospore; VIII, zygospore . r 1 forming a large swarm spore, which is free in colonies separate from the parent IX; X, same large swarm spore divided to , . form young colony. (After Pringsheim.) and grow to the normal size. Sexual reproduction takes place when these small individuals separate and conjugate in pairs, usually a small one w^ith a large one, producing a zygospore. Some of the colony algae are non- motile as in the water-net (Hydrodictyon), FILAMENTOUS GREEN ALG^. The Confervas {Confervoidece). 363. General characters.—The larger number of these algae are thread-like, either simple or branched, forms are leaf-like, as the ''sea ; Some of the marine The chlorophyll is. Please note that these images are extracted from scanned page images that may have been
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1910
