EFFECT OF ANESTHETICS UPON LIVING PROTOPLASM. 311 



long enough. After a few hours ether is decidedly harmful to 

 higher animals, and yet no one would question its claim to being 

 an anesthetic. Other anesthetics produce more marked injuries. 

 There is every gradation between those which produce slight in- 

 jury and those which cause considerable damage. Where then 

 shall we draw the line? I propose to consider as an anesthetic 

 any substance which stops a vital process without killing the 

 cells in which the process occurred. We can then distinguish 

 between the less injurious and the more injurious anesthetics. 



In the following table all the substances listed produce anes- 

 thesia in the sea-urchin egg. The concentrations represent per 

 cents, in sea-water. At the concentration indicated in the first 



Anesthetic Lethal 



concentration concentration 



Ether 2 % 4 % 



Chloroform 0.13% i % (emulsion) 



Chloral hydrate 0.25% i % 



Nitromethane 2 % 3 % 



Paraldehyde 4 % 8% 



Acetone 5 % 10 % 



Ethyl nitrate 0.4 % 



Ethyl acetate 2 % 5 % 



Ethyl butyrate 0.25 % 0.5 % 



Acetonitrile 4 % 5 % 



Propyl alcohol (normal) i % 



Amyl alcohol 0.6 % i % 



Phenyl urethane 4/5 saturated saturated (= < 0.5%) 



Ethyl urethane 1.5 % 3 % 



column, in every case a marked lowering of the viscosity of the 

 egg protoplasm could be demonstrated. This was proven by 

 centrifuge tests. Normal eggs in sea-water and anesthetized 

 eggs were centrifuged simultaneously, the normal eggs being 

 placed in one tube, the anesthetized eggs in another. At a speed 

 which produced no movement of granules in the cytoplasm of 

 the normal eggs, the granules in the cytoplasm of the anes- 

 thetized eggs were thrown completely into one half of the egg. 

 The difference was in every case very striking. The normal 

 eggs appeared evenly opaque. The anesthetized eggs had half 

 or more of their cytoplasm perfectly transparent. The viscosity 

 of the anesthetized cytoplasm was undoubtedly many times less 

 than that of the normal eggs. 



