DEFECTIVE PLUTEUS LARVÆ FROM ISOLATED BLASTOMERES OF ARBACIA AND ECHINARACHNIUS

摘要: Ever since Driesch in I891 announced that a single blastomere of the two cell stage sea-urchin's egg separated by shaking would develop into whole larva half size, this method has been generally used embryologists for determining type organization present various eggs at time first or later cleavages. Driesch's conclusions led to much controversy, but most investigators have come fairly definite agreement on major facts be learned from field investigation, and turned other problems. The recent important work Von Ubisch (I925) once more drawn attention sea-urchin previous cleavage, made it necessary revise certain accepted ideas. data which I shall appear significance connection, even though late date seem impossible add anything regarding development isolated blastomeres eggs, will my excuse briefly reviewing evidence. In I900 I906 repeated amplified his earlier stated conclusion sea urchin there was no evidence differentiation any cleavage stage, an harmonic equi-potential system, each might give rise part larva. I90I. Boveri studied normal blastomeres, concluded entoblast zone below