PLATE 4 



EXPLANATION OF FIGURES 



Chaetopterus. Development in KNC m/100000 



17 A B Distended type in KNC and HCl from thirty minutes after fertiliza- 

 tion. 



18 A B Larval form showing differential inhibition and partial recovery. 

 KNC eleven hours, beginning forty-five minutes after fertilization; then re- 

 turned to sea water. 



A lateral, B ventral view. 



50 



