PLATE 7 



EXPLAN'ATIOX OF FIGURES 



Nereis. Xormal and inhibited development 

 24 to 27 Xormal development; one, one and one-half, two and one-half and 

 four and one-half days. 



28 Stage attained after three days in KXC w, 50000, beginning just before 

 first cleavage. 



29 Four days in KXC ?n 100000 from stage just before cleavage. 



56 



