592 RALPH S. LILLIE 



action which is dependent upon the change of permeabihty. 

 Since anesthetics, as well as calcium and magnesium, render 

 the plasma-membrane more resistant to the permeability-in- 

 creasing action of salt-solutions/ they ought — if the above point 

 of view is correct — also to prevent the cleavage-initiating action 

 of these solutions. It was with this expectation that the follow- 

 ing experiments were begun. 



A well-marked antagonism of this kind was readily demon- 

 strated in Arbacia eggs, although again as with the above anti- 

 cytolytic action the anesthetics were found to be less effective 

 than calcium or magnesium. The same anesthetics were used 

 as in the preceding experiments with fertilized eggs,^ in the con- 

 centrations there found just sufficient to prevent cell-division. 

 The addition of anesthetics to the pure salt-splutions used (0.55 

 m KCNS and Nal) was found in many instances greatly to de- 

 crease the cleavage-initiating action of these solutions. Many 

 of the eggs after exposure to the anesthetic-containing salt- 

 solutions for five minutes remained to all appearance unchanged, 

 while those treated similarly with the same salt-solution, free 

 from anesthetic, all formed fertilization-membranes and under- 

 went change of form or cleavage.^ 



The different anesthetics, however, were found to vary greatly 

 in their ability thus to prevent the characteristic action of the 

 salt-solution without injury to the eggs. Chloral hydrate and 

 the urethanes proved much less effective in this respect than the 

 alcohols, although, as shown in my paper on the influence of 

 anesthetics on cleavage,^ they are more favorable for anesthetiz- 

 ing the cleavage-process. The ability to counteract the salt- 

 action thus need not run parallel with the power of suppressing 

 cleavage. The case of potassium cyanide affords a further illus- 

 tration of this difference in the influence of the same compound 

 on these two processes. Cyanide does not appreciably interfere 



" Loc. cit., 1912. 



^Cf. Jour. Biol. Chem., 1914, vol. 17, p. 121. 



^ Aftei--treatment with hypertonic sea-water is, of course, necessary to make 

 such eggs develop to advanced stages. 

 'Loc. cit., 1914. 



