DEFECTIVE PLUTEUS LA R V.I-:. 



injured and therefore tailed of normal development, but in view 

 of the evidence given in the next table where the development of 

 pairs from the same egg are listed, it is probable that some of 

 them were deficient in cytoplasmic material already localized at 



FIG. 3. Pluteus larva> lour days old developed from single blastomeres of the 

 two cell stage of Arbacia. A is a larva with a complete skeleton of approximately 

 one half size. B, C, and D are larvae with defective skeletons. Measured and 

 drawn free hand to the same scale from living specimens. 



