WATER 



s 





:4 R'^ -cfi ■■^;-S^'^> 



%? 



#: 





**'.* 



^ «••• 



* *• 







fi 



Fig. 20(^. — Same history as that of Fig. 20c, but a still later stage of development. 





# 



-■r«- 



XL.y 



c\ 







M (^.:W^ 



.^ 



'ia 'O 



W" ^ 





Fig. 20f. — Egg of Platynereis megalops showing water-drops in cells of a late 

 cleavage-stage on return to sea-water following exposure to 40 per cent, sea-water 

 for one hour. 



133 



