KiG 73 A-I -Echinoid development under natural and slightly inhibiting conditions. 

 A-E development of Dendraster excentricus from gastrula to pluteus under natural conditions; 

 F, G, pluteus of Arbacia punctulata; H, I, slight differential inhibition of Arbacta pluteus by de- 

 velopment in KCN m/ 100,000 {F-I from Child, igibb). 



