182 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 



Fig. 46 



Fig. 47 



Fig. 48 



Fig. 49 



Fig. 50 



Fig. 51 



Membrane formation and cytolysis of the sea-urchin egg under the influence of 



salicyl aldehyde. 



FIGS. 46-49. Successive stages in the formation of the membrane. 

 FIG. 50. Beginning of cytolysis. 

 FIG. 51. Complete cytolysis. 



