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ROBERT CHAMBERS. 



the investing membrane. Such an egg is capable of forming a 

 normal fertilization membrane when inseminated. If the pushing 

 process be carried too far, a distinctive quiver can be recognized, 

 as of something giving way. On subsequent insemination such 



FIG. 17. a and b, successive steps, in pulling a starfish egg out of its 

 fertilization membrane, c, empty membrane at 4 :oo P.M. d, ditto four hours 

 later at 8 :oo P.M. The membrane persists as a collapsed remnant for a 

 long time. 



eggs produce a collapsed fertilization membrane. The quiver 

 undoubtedly was due to a rupture of the egg membrane. On 

 account of this rupture the fluid, which presumably collects under 

 the membrane, leaks out and the membrane is not lifted uni- 

 formly. 



4. THE CORTEX AND INTERIOR OF THE UNFERTILIZED EGG. 



The cytoplasm of the immature starfish egg is uniformly semi- 

 solid. A gash made in it with a needle is maintained for some 

 minutes before closing up. When the germinal vesicle breaks down 

 naturally, the egg protoplasm becomes more fluid so that a gash 



