Sex [electronic resource] . east like agreen plant. But let us consider its repro-ductive relations. It occasionally happens that a componentunit of the ball of cells may become repro-ductive and divide to form a daughter-colony(see Fig. 4a) without more ado. This is analmost vegetative way of multiplying, atleast a parthenogenetic one. But in other -DC Fia. 4a.—A Volvox colony showing in the interior fourdaughter-colonies (DC), produced asexually. (After Klein.) conditions, when nutrition is checked, a lessdirect mode of reproduction occurs. Some ofthe cells in the living ball become large, w
Sex [electronic resource] . east like agreen plant. But let us consider its repro-ductive relations. It occasionally happens that a componentunit of the ball of cells may become repro-ductive and divide to form a daughter-colony(see Fig. 4a) without more ado. This is analmost vegetative way of multiplying, atleast a parthenogenetic one. But in other -DC Fia. 4a.—A Volvox colony showing in the interior fourdaughter-colonies (DC), produced asexually. (After Klein.) conditions, when nutrition is checked, a lessdirect mode of reproduction occurs. Some ofthe cells in the living ball become large, well-fed elements—the ova; others, less anabolic,fade from green to yellow, divide and re-divide into many minute units—the sperma-tozoa. Here we see the formation of dimorphicreproductive cells in different parts of thesame organism. But we may also find Volvoxcolonies in which only ova are being produced THE EVOLUTION OF SEX 25 (see Fig. 4b), and others in which only spermsare being produced (see Fig. 4c). The former. Fig. 4b.—A Vol vox colony in a female phase, producingnumerous ova or egg-cells (E). (After Klein.)
Size: 1603px × 1559px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpublishernewyorkhholtandcom
