182 ArtTiFIcIAL PARTHENOGENESIS AND FERTILIZATION 
Membrane formation and cytolysis of the sea-urchin egg under the influence of 
salicyl aldehyde. 
Fics. 46-49.—Successive stages in the formation of the membrane. 
Fig. 50.—Beginning of cytolysis. 
Fic. 51.—Complete cytolysis. 
