“…The reality of the animal-vegetal, dorso-ventral and anterio-posterior gradients in the RNA distribution of blastulae, gastrulae and neurulae has been confirmed by quantitative estimations (Brachet, 1942;Steinert, 1951;Takata, 1953;Pfautsch, 1960). It bas been generally assumed that RNA and proteins are metabolically inert before gastrulation.…”