. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 184 WESLEY R. COE of an occasional hermaphrodite, all individuals of both species are strictly uni- sexual and the two sexes are approximately equal in number. A different type of gonad is found in both the larviparous and oviparous oysters (Ostrea), in scallops (Pecten), mussels (Mytilus, Volsella), and numerous other bivalves. In these the gonads are composed almost entirely of gametogenic cells which receive their nourishment directly from the sourrounding vesicular connective tissue. The follicle cells are few and small
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 184 WESLEY R. COE of an occasional hermaphrodite, all individuals of both species are strictly uni- sexual and the two sexes are approximately equal in number. A different type of gonad is found in both the larviparous and oviparous oysters (Ostrea), in scallops (Pecten), mussels (Mytilus, Volsella), and numerous other bivalves. In these the gonads are composed almost entirely of gametogenic cells which receive their nourishment directly from the sourrounding vesicular connective tissue. The follicle cells are few and small (Figures 5, 6). As the gonadal follicles increase in size the surrounding nutritive connective tissue is utilized. The larviparous oysters, of which Ostrea lurida may serve as an example, exhibit changes in sexuality during life, the sequence of sexual phases being similar. FIGURE 7. Anomia simplex. A, portion of primary gonad surrounded by nutritive tissues (nf). B, follicles of mature ovary in which the nutritive tissues'(nf) have been almost assimi- lated; bv, blood vessels; m, mantle; gd, genital duct. to those mentioned for Teredo navalis (Coe, 1934). In the oviparous oysters, as 0. mrginica, there is likewise a strong tendency toward protandry, since about 70 per cent of the young individuals first function as males (Coe, 1938). The primary gonad usually contains antecedent cells of both sexual types (Figure 6, A). Functional hermaphroditism occurs occasionally and a few individuals change from the male to the female phase during their first spawning season. Thereafter the individual functions in one sexual phase or the other during all of each spawn- ing season, but not infrequently the sexual phase changes between two spawning seasons (Burkenroad, 1937; Galtsoff, 1938; Coe, 1938; Loosanoff, 1942). In. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustratio
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
