174 PROTOPLASMIC ACTION AND NERVOUS ACTION 



Pure salt solutions (NaCl) or solutions of acid or alkali 

 alter the membrane and allow penetration. Character- 

 istic antagonisms are shown in these effects;^ e.g., the 

 penetration of heavy metal salts (cobalt and nickel) is 

 retarded by CaClz and their toxic action is thus pre- 

 vented.^ Eggs placed in pure strongly hypertonic 

 NaCl solutions float at first, but soon sink and die, 

 indicating the penetration of salt and water as the 

 membrane is altered; but in the same solution to which 

 CaCla has been added, they may float and remain 

 living for several days.^ Recently Loeb and Cattell have 

 studied the penetration of K salts and acids into the 

 Fundulus egg in the presence of other salts (alkali and 

 alkah earth) in varying concentrations."* As index of 

 the penetration of KCl the paralyzing action of the salt 

 on the heart was used; this action is reversible, so that 

 if eggs containing embryos whose hearts have previously 

 been arrested in KCl solution are placed in sea water, the 

 heartbeat after a time revives, indicating outward 

 dift'usion of KCl through the membrane. The remark- 

 able fact is that this recovery does not occur in distilled 

 water or in solutions of non-electrolytes; in order that 

 the potassium shall penetrate the membrane, a treatment 

 of the latter with salt solutions is necessary. Thus 

 (typically) all of the poisoned hearts resume beating 

 within a day when the eggs are placed in sea water or 



' Cf. the article by J. Loeb in Oppenheimer's Handhuch der Bio- 

 chemie, II, 104, for a general account of antagonisms in Fundulus eggs. 



'A. P. Mathews, American Journal of Physiology, XII (1905), 419. 



3 Loeb, Science, XXXVI (1912), 637; Biochem. Zeitschrijt, XL VII 

 (1912), 127. 



4 Loeb and Cattell, Journal of Biological Chemistry, XXIII (1915), 

 41; Loeb, ibid., XXVII (1916), 339, 352, 363; XXVIII, 175. 



