1 66 PROTOPLASMIC ACTION AND NERVOUS ACTION 



toxic effects by counteracting the structural change in 

 the membrane.^ 



The question of just how, in the physico-chemical 

 sense this result is accomplished is a fundamental one; 

 salt antagonism is shown by all groups of organisms from 

 bacteria^ to vertebrata, and is apparently a universal 

 phenomenon in living protoplasm. It should be noted 

 that other effects produced by the pure Na salt solu- 

 tion are also antagonized by Ca and other salts; e.g., its 

 stimulating action, shown in the production of twitches 

 in vertebrate and other muscle,^ the sensitizing action 

 on muscle just described, and the activation of unfertil- 

 ized eggs."* The fact that prevention (by Ca and nar- 

 cotics) of increase of permeability in various irritable 

 tissues and organisms is associated with prevention of 

 stimulation has a general interest as evidence of the 

 essential part played by membranes in stimulation, and 

 will be considered more fully later. 



The problem of the physico-chemical basis of salt 

 antagonism has been approached in various ways and 



^ Osterhout, loc. cit. Related observations are those of Ham- 

 burger on the action of calcium in preventing the increase in perme- 

 ability produced in frog's kidneys perfused by NaCl solutions containing 

 dextrose (cf. Hamburger, Biochem. Zeitschrift, LXXXVIII [1918], 97). 

 In 1904 J. B. MacCallum had observed the antidiuretic action of calcium 

 salts and had related it to the action in decreasing permeability (Journal 

 of Experimental Zoology, I [1904J, 179; University of California Pub- 

 lications, Physiol., II [1905], 93). It is weU known that calcium antago- 

 nizes cytolysis by saponin and other permeability-increasing compounds. 

 Chiari's observations on the formation of exudates and many other obser- 

 vations are related; cf. Hober, op. cit., pp. 544 £F. 



* For the case of bacteria cf. Shearer, Journal of Hygiene, XVIII 

 (1919), 339- 



3 Cf . Loeb's article in Festschrift fur Fick, loc. cit. 



4 R. S. LilHe, American Journal of Physiology, XXVII (1911), 289; 

 Journal of Morphology, XXII (191 1), 695. 



