THE PERMEABILITY OF PROTOPLASM 129 



The alteration in permeability produced by an alkaline 

 medium has formed the subject of a recent paper by Oster- 

 hout (1914, 4). Warburg (1910) noticed that the rate of 

 oxidation in the egg of the sea-urchin increased when the 

 surrounding sea-water was made faintly alkaline, even 

 though the sodium hydroxide used to produce this effect 

 failed to penetrate into the egg, as was shown by previously 

 staining the latter with an indicator. This peculiar oc- 

 currence was thought by Osterhout to be due to an alteration 

 in the permeability of the egg, for oxidation would be 

 increased if either the entry of oxygen or the exit of the 

 products of oxidation were facilitated. This surmise was 

 fully borne out by experiment. For example, it was found 

 that the electrical resistance of discs of the thallus of 

 Laminaria saccharina decreased rapidly when placed in 

 sea-water rendered alkaline to the extent of containing 

 0-0052 gramme - molecule of sodium hydroxide per litre. 

 The fall amounted to about 70 per cent, of the original 

 value. When placed in a solution of the chlorides of 

 sodium and calcium containing considerable quantities 

 of the latter, the resistance increased at first, and then de- 

 creased. The addition of sodium hydroxide to such a solu- 

 tion caused the initial rise to be less noticeable, and dimin- 

 ished the time required for the fall to take place. Very 

 dilute alkaline solutions were, however, without effect; 

 thus 0-001 M sodium hydroxide and all weaker solutions 

 are harmless. W T ith these results the conclusions of Loeb 

 and Wasteneys (1913) are in agreement. These authors 

 repeated Warburg's experiments, and found that O'OOl M 

 sodium hydroxide had no accelerating action upon the 

 oxidations taking place in the egg of the sea urchin. 

 Higher concentrations injured the egg and raised the 

 rate of oxidation. 



The possibility that the antagonistic action of salts might 



