27O LIBBIE H. HYMAN. 



known that a number of chemical substances as well as other 

 agents will induce a fertilization membrane in echinoderm eggs. 

 This matter has been discussed from the point of view of mem- 

 brane formation by Traube ('09), Loeb ('13), Gray ('22) and 

 others and from the point of view of membrane elevation by 

 Heilbrunn ('13, '15). I have made a few observations on artifi- 

 cial membrane elevation, using chiefly ether and diluted sea- 

 water or distilled water but also butyric acid. In employing 

 ether and similar substances for membrane elevation, the eggs 

 must be rapidly returned to normal sea-water, as noted by Loeb 

 ('13) if any are to be saved from cytolysis. 



After the application of membrane-elevating substances such 

 as ether and distilled water, three classes of eggs are noted: those 

 with blister-like elevations, those with completely elevated 

 membranes, and those which are cytolyzed. In a considerable 

 number of eggs after treatment with ether and distilled water, 

 the membrane is elevated only as local blisters. In one or two 

 cases such blisters were observed to spread over the egg until 

 the entire membrane was elevated but generally they persist 

 unchanged as long as observed (unless cytolysis intervenes). 

 They appear to be due to chance inequalities of contact with the 

 membrane-elevating solution when the latter is first applied and 

 indicate that the local action of such solutions is incapable of 

 inducing complete membrane elevation. Such partially elevated 

 membranes can be completed by sperm. The portions elevated 

 by sperm appear to be continuous with those elevated by the 

 agent. 



After treatment with ether and distilled water there is obtained 

 a small percentage of eggs in which the membrane is completely 

 elevated and which cannot be distinguished visibly from eggs 

 fertilized by sperm. Investigation with the needle shows, how- 

 ever, that as concerns viscosity conditions these eggs are entirely 

 different from normally fertilized eggs. Whereas in the latter, 

 as already noted, the cytoplasm has undergone gelation, in these 

 eggs with artificially elevated membranes there is no trace of 

 such increased viscosity. These latter eggs are as fluid as or 

 more fluid than normal unfertilized eggs. This agrees w r ith 

 Heilbrunn's ('2oc) statement that ether, chloroform, and similar 



