354 RALPH S. LILLIE. 



Lately many investigators have concurred in this view that 

 alterations in the physico-chemical properties of the plasma- 

 membrane form the essential basis of anaesthesia. Whatever 

 condition alters this structure so as to make it less capable of 

 undergoing the changes of permeability and of electrical polariza- 

 tion which normally accompany stimulation and apparently 

 other forms of cell-activity has an inhibiting or paralyzing 

 effect on the cell. This general view has been reached as the 

 outcome of a large number and variety of investigations. Over- 

 ton in 1904 pointed out that the paralyzing action of potassium 

 salts on voluntary muscle must be referred to their action on the 

 membrane, since plasmolytic experiments indicate that such salts 

 do not penetrate into the cell interior. 1 The view that the 

 physiological action of neutral salts is due primarily to their 

 influence on the plasma-membrane was later strongly supported 

 by Hober 2 on the basis of experiments on the influence of neutral 

 salts on the demarcation-current potential of muscle. This 

 may be influenced in the direction either of increase or decrease 

 by treatment with isotonic solutions of sodium and other salts. 

 Salt solutions, like those of potassium salts, which decrease this 

 potential i. e., produce local negative variation apparently 

 do so by altering the colloids of the plasma-membrane and so 

 increasing its permeability; in general such increased permea- 

 bility to ions involves decrease in the electrical polarization of 

 the membrane (i. e., negative variation); increased polarization 

 means an alteration of the membrane in the reverse direction, 

 i. e., of decreased permeability. These changes of polarization 

 and permeability result from the altered condition of the colloids 

 forming the membrane. The colloidal system of the membrane 

 acquires in the presence of certain salts a less dense consistency 

 ("Auflockerung") associated with increased permeability; and a 

 denser consistency ("Verdichtung") in the presence of others, 

 e. g., sodium iodide, etc. The microscopic appearances observed 



the Permeability of the Limiting Membranes," in Amer. Journ. Physiol., 1911, 

 Vol. 28, p. 197. Also, for a more elementary treatment, the articles "The Role of 

 Membranes in Cell-Processes," and "The General Physico-chemical Conditions 

 of Stimulation," in the Popular Science Monthly, 1913 and 1914. 



1 E. Overton, Pfliiger's Archil), 1904, Vol. 105, p. 176; cf. p. 207. 



2 R. Hober, Pfliiger's Archiv, 1905, Vol. 106, p. 599. 



