. The algae. Algae. 26 THE ALGAE being the normal number in the common species P. morum. In the species the cells are so compacted that they are flattened by mutual pressure. Each colony is enclosed in a gelatinous matrix with an outer watery sheath, and, together with the next two genera, exhibits some degree of polarity in its progression. In asexual reproduction the colony first ceases to be motile and sinks to the bottom of the pond. Then each cell gives rise by several divisions to a bowl-shaped daughter colony or coenobium. This. A B Fig. 5 Pandorina morum. A, vegetative colony ( x 975).
. The algae. Algae. 26 THE ALGAE being the normal number in the common species P. morum. In the species the cells are so compacted that they are flattened by mutual pressure. Each colony is enclosed in a gelatinous matrix with an outer watery sheath, and, together with the next two genera, exhibits some degree of polarity in its progression. In asexual reproduction the colony first ceases to be motile and sinks to the bottom of the pond. Then each cell gives rise by several divisions to a bowl-shaped daughter colony or coenobium. This. A B Fig. 5 Pandorina morum. A, vegetative colony ( x 975). B, colony with female gametes ( x 975). (After Smith.) becomes inverted and assumes a spherical shape after which each cell produces two flagella. The daughter colonies are ultimately liberated by disintegration of the parent envelope. In sexual re- production there is a sUght tendency to anisogamy, the male gametes being more active than the female. When the zygote ger- minates it produces one to three biflagellate swarmers, which, after a period of motility, come to rest and divide to give new colonies. Another simple colonial member like Pandorina is Volvulina steinii with 16 cells arranged in four tiers of four. Volvocaceae: Eudorina {eu^ well; dorina^ meaningless). Fig. 6 The colonies are spherical or eUipsoidal, the posterior end often being marked by mamillate projections. They contain sixteen, thirty-two (commonly) or sixty-four biflagellate cells, which are not closely packed and are sometimes arranged in transverse rows. The flagella of the individual cells emerge through funnel-shaped canals. Sometimes the coenobitmi becomes an amorphous palm- elloid mass, and then when conditions once more become suitable individual cells break away and grow into new coenobia. In most. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resembl
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Keywords: ., bo, bookcentury1900, bookcollectionbiodiversity, booksubjectalgae
