164 The Mechanistic Conception of Life 



unfertilized egg is perhap?= still more striking. The egg of the 

 Atlantic form of sea-urchin, Arbacia, is cytolyzed in a neutral 

 sodium chloride solution in a few hours, while the unfertilized egg 

 may live for a considerably longer period of time. When we 

 put fertilized and unfertilized eggs into hypertonic solutions, 

 we find also that the fertilized eggs suffer much more than the 

 unfertilized. What causes this difference of sensitiveness 

 between fertilized and unfertihzed eggs? It is possible that 

 the permeability of the fertilized eggs is greater than that 

 of the unfertilized. While this is probably to some extent 

 true, yet it is not the whole explanation of the difference in the 

 behavior of the two kinds of eggs. I have been able to show for 

 a number of toxic solutions that their effect can be either com- 

 pletely annihilated or at least diminished if we take the oxygen 

 away from the solution. Thus, for instance, fertilized eggs of 

 the sea-urchin which perish very rapidly in pure salt solutions, 

 or a solution of sodium -f- calcium, or a solution of sodium -|- 

 barium, can be kept alive for a considerable period of time in 

 the same solutions if we either carefully remove the oxygen from 

 the solutions, or if we diminish the rate of the oxidations in the 

 eggs by adding a trace of sodium cyanide. In this case we have 

 the direct proof that solutions which are fatal for the egg when 

 the oxidations are allowed to go on are rendered completely, or 

 at least partially, harmless if we stop the oxidations in the egg. 

 Not only the toxic action of salt solutions upon the fertilized 

 egg could be inhibited by the suppression of the oxidations in the 

 egg, but also the toxic action of sugar solutions, or of solutions of 

 alcohol in the sea-water, or of a solution of chloral hydrate.' 



These observations prove directly that in the presence 

 of certain toxic substances or mixtures of substances the 

 oxidations in the egg lead to its rapid destruction; while a 

 suppression of the oxidation saves the life of the egg. 



' Or of phenylurethane. This observation does not agree very well with the 

 assumption that the narcotic action of these substances is due to a retardation of 

 oxidation. 



