. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 264 PHILIP A. BUTLER The orderly sequence of events in the development of functional gametes in the American oyster has been described (Coe, 1932; Loosanoff, 1942), and the resume of the stages given here for the HS oysters growing in Chesapeake Bay differs in no important respect from conditions found elsewhere except with regard to timing (Loosanoff and Engle, 1940). Spawning is initiated when water tempera- tures rise to levels approximating 18 to 20° C, and consequently its occurrence varies from year to year at any part
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 264 PHILIP A. BUTLER The orderly sequence of events in the development of functional gametes in the American oyster has been described (Coe, 1932; Loosanoff, 1942), and the resume of the stages given here for the HS oysters growing in Chesapeake Bay differs in no important respect from conditions found elsewhere except with regard to timing (Loosanoff and Engle, 1940). Spawning is initiated when water tempera- tures rise to levels approximating 18 to 20° C, and consequently its occurrence varies from year to year at any particular geographical location. Typically, after the final spawning of the population in late summer, there is a short period of rest in which the gonadal tissue is made up of undifferentiated gonial cells. These soon proliferate and early maturation takes place. By this time, usually late Decem- ber in Chesapeake Bay, water temperatures have decreased to the extent that the oyster becomes inactive and the gonad remains quiescent until the following March. Thus in early spring, gonad sections from the HS oysters are characterized by fairly large numbers of auxocytes. As water temperatures increase, differentiation and growth proceed at a rapid pace, and mature gametes first appear in May when spawning may begin. In June most of the gonads are filled with ripe sexual products, and from that time until early September, successive waves of spawning may continue. By the end of September the majority of gonads are in the resting condition. In contrast to this typical picture, section of the gonads of the LS group revealed that 5 to 40 per cent of each sample contained gonads which were in the resting Early Maturation Goniol Proliferation Resting Gonlols_ Spawned Out Partially Spawned. Mature Gametes. Late Maturation Early Maturation Gonlat Proliferation Retting Gonioli. * 1 1 I 1 . L L_ ' May June July Auguit September October November December Jonuory FIGURE 1. Seasonal progression
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
