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 

 CaCL 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 

 Fundiilus 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 

 diffusion of KCl through the membrane. The remark- 

 able fact is that this recovery does not occur in distilled 

 w^ater or in solutions of non-electrolytes; in order that 

 the potassium shalf 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 Handhiich der Bio- 

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



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



3 Loeb, Science, XXXVI (191 2), 637; Biochem. Zeitschrift, XL VII 

 (1912), 127. 



4 Loeb and Cattell, Journal of Biological Chemistry. XXIII (191 5), 

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



