2Q2 WALTER E. CARREY. 



Experiments by the writer have shown that when fertilized 

 eggs of Asterias or Arbacia are placed in a two per cent, solution 

 of Witte's peptone in sea water the fertilization membrane 

 crumples instantly as in Loeb's experiments, but that when 

 allowed to remain in the solution the membranes are again 

 distended, indicating that they are slowly permeated by the 

 albumoses in this preparation. Such results can only be ob- 

 tained where a semi-permeable membrane, one permeable to 

 salts but impermeable to colloids, encloses a space containing a 

 colloidal solution. 



4. Still other facts show that the space between the fertiliza- 

 tion membrane and the egg surface is filled with a fluid and not 

 with a gel. If Asterias eggs are heated to 33 C. they form 

 fertilization membranes in from three to five minutes. By 

 further warming for fifteen minutes they show slow amoeboid 

 movements after they have been returned to sea water at 20 C. 

 They may migrate about in the space enclosed by the thin 

 fertilization membrane and up close to that structure at any 

 point. They may throw out long streamer like pseudopodia 

 which meet with no check to their progress anywhere in the 

 space till they reach the thin confining fertilization membrane. 

 This over-heating process may lead to droplet formation and 

 ultimately to partial or complete disintegration of the egg; 

 tne debris thus formed is scattered throughout the space and is 

 never held away from the thin fertilization membrane by any 

 gelatinous structure. Similarly if the fertilized eggs of Asterias 

 are subjected to the action of diluted sea water they may be 

 caused to swell until each presses tightly against the confining 

 fertilization membrane and completely fills the space. Cytolysis 

 will result in sea water which has been sufficiently diluted and 

 in this case, as in that of cytolysis caused by prolonged warming, 

 the granular material completely fills the perivitelline space 

 which may be more than twice the original diameter of the egg. 

 When extra-ovates rupture through the fertilization membrane 

 after treatment with hypotonic solutions, the egg is drawn over 

 tightly against the inner surface of the membrane at the point 

 of rupture, the thinness of the membrane being evident at the 

 constricted neck between the extra-ovate and the main egg mass. 



