Preliminary observations reported hereafter on the morphogenesis of Amphibian embryos (Anura) show that hydrostatic pressure of an order of magnitude of 200-300 atm. brings about partial inhibition of gastrulation (i.e. morphogenesis does not proceed beyond initial dorsal lip formation), whereas in embryos to which pressure was applied at the neurula stage (just elevated neural folds) neural tube fusion is accomplished along a pattern superimposable to that of the control embryos, grown at normal hydrostatic pressure.