(el 



(f) 



Plate IV 



Dissolution of egg membrane of Megathura cyemilata bv an extract 

 of a 1% homologous sperm suspension, a, i min., b, 1-75 min., 

 r, 2-00 min., d, 2-25 min., e, 3-00 min.,/, 3-25 min. after addition 

 of extract. Photograph by A. Tyler. 



