322 RALPH S. LILLIE. 



irritability and automatic activities of the cell. This general 

 conception is of the greatest importance in the theory of anaesthe- 

 sia, and will be reconsidered later. 



The most important instances of anaesthesia are those produced 

 by chemical substances. First it should be noted that substances 

 belonging to the most various classes may have anaesthetic effects. 

 This fact is overlooked in theories like those of Overton and 

 Meyer, Traube, and others, which refer anaesthesia to the special 

 properties of lipoid-solvent substances, which are regarded as 

 acting either by dissolving in the lipoid constituents of the cell 

 or by adsorption at the surfaces of membranes or other structures. 

 The anaesthetic influence of certain neutral salts shows, however, 

 that lipoid-solubility or surface activity is not essential to narcotic 

 action; magnesium sulphate has long been used by naturalists 

 to narcotize marine animals; more recently it has been applied 

 by Meltzer to produce spinal anaesthesia in mammals. Similar 

 reversible depressant effects are produced by potassium salts. 

 Salts of calcium and strontium also cause reversible desensitiza- 

 tion of isolated nerve and muscle. In most animals the calcium- 

 content of the medium has marked influence on irritability and 

 automatic activity; this is well shown in the case of vertebrate 

 muscle; lowering the ratio of calcium to sodium in indifferent 

 media like Ringer's solution has a sensitizing effect, and if the 

 calcium falls too low the muscle twitches spontaneously; increas- 

 ing the calcium-sodium ratio has a desensitizing action; these 

 effects are reversible. 1 Calcium also antagonizes the stimulating 

 and sensitizing action of pure solutions of sodium and other salts 

 on muscle and nerve. Similarly the heart beats best in media of 

 a certain calcium-content. In marine medusae (Rhizostoma ac- 

 cording to Bethe) the rhythmical beat ceases when the animal is 

 transferred to calcium-free sea water, and is restored if calcium 

 is added; still further addition of calcium again arrests the move- 

 ment. 2 These facts make it clear that alteration of the salt- 

 content of the media may have effects essentially identical with 

 anaesthesia. This is a fact of much theoretical interest, since it 

 indicates that the general condition of the colloids of the cell, 



1 For instances of these various effects cf. J. Loeb's article on "Physiological 

 Actions of Ions," in Oppenheimer's " Handbuch der Biochemie," 1909, Vol. 2, p. 104. 



2 Cf. Bethe, Pfliiger's Archiv, 1909, Vol. 124, p. 561. 



