Reported in this paper are results obtained from investigations into the effect of hypergravitation on embryogenesis of striped muscles in Japanese quail. Specimens of striped muscles were excised from the birds after hatching and used in the study. The eggs had been centrifuged on zero day as well as on the first and 15th days of incubation. The muscle fibrils were found to proliferate in all groups, that is the control group, the group with centrifugation on zero day, and that with centrifugation on the first and 15th days. The process thus is characterised as physiological, known to occur prenatally and postnatally in developing individuals.