46 RALPH S. LILLIE 



III. SUMMARY 



The chief experimental results and theoretical conclusions of 

 the present paper may be briefly summarized as follows. 



1. Temporary exposure of unfertilized starfish eggs to pure 

 isotonic NaCl solution, to sea-water containing fatty acid, or to 

 high temperature (35°), is followed by the formation of fertili- 

 ization-membranes and cleavage, and a certain proportion of 

 eggs so treated (usually from 1 to 5 per cent) may develop to a 

 larval stage. If, after membranes are formed, the eggs are treated 

 for thirty minutes with hypertonic sea-water or weak cyanide 

 solution, the proportion thus developing is usually increased, often 

 to a marked degree. 



2. The same effect is produ-ced in Asterias eggs by after- 

 treatment with solutions of various anesthetics in sea-water, 

 namely, ethyl ether, ethyl urethane, chloral hydrate, chloretone, 

 various alcohols (ethyl, propyl, butyl, amyl, capryl). Arbacia 

 eggs do not respond to this treatment. 



3. The anesthetics exert this favorable action in concentrations 

 corresponding closely to those causing typical anesthesia in 

 Arenicola larvae. The essential effect of this treatment upon 

 the egg is thus probably of the same nature as that which con- 

 ditions anesthesia in irritable tissues. This effect appears to 

 consist in imparting to the plasma membranes either a degree 

 of permeability which is less than the normal, or an increased 

 resistance to agencies whose general action is permeability- 

 increasing (that is, cytolytic, if the action is not compensated 

 or reversed within a certain time). 



4. The above anesthetics have been shown to exert a protec- 

 tive or anticytolytic action on starfish eggs in the presence of 

 certain cytolytic agents (pure salt-solutions). Their action in 

 preventing the disintegration of eggs after artificial membrane- 

 formation, and in thus rendering possible the continuance of 

 development, is probably an effect of the same essential kind. 



