THE THEORY OF ANESTHESIA. 321 



the same effect on the rate of oxidation results from a simple 

 lowering of temperature by 2 to 3, a change which only slightly 

 retards cell-division. Decrease in the rate of oxidation as such 

 is thus quite insufficient to account for the inhibitory effect. 

 The fact that, e. g., in frogs' muscle a lowering of temperature 

 of 20 (e. g., from 35 to 15) which reduces the rate of oxidation 

 to one fifth of its former value leaves irritability unimpaired, 

 indicates that any explanation of anaesthesia based on simple 

 decrease in reaction-velocity is inadmissible. A similar decrease 

 in the rate of oxidation can be produced by lipoid-solvent 

 anaesthetics only in concentrations which are much higher than 

 those requisite for anaesthesia. 



The constant electric current produces in many irritable tissues 

 effects closely resembling true anaesthesia. Many physiological 

 inhibitions may be caused by passing a constant current through 

 the tissue. There is indeed reason to believe that many of the 

 normal inhibitions, e. g., in the neurones of reflex arcs, are elec- 

 trical in their nature. 1 The anti-stimulating or desensitizing 

 action of the constant current thus deserves careful consideration 

 in any general theory of anaesthesia. As is well known, the 

 action of the current on irritable tissues like nerve and muscle 

 is polar; where the current enters the tissue there is decreased 

 irritability, depression, or inhibition (anelectrotonus) ; where it 

 leaves there is excitation or heightened irritability (catelectro- 

 tonus). Thus a nerve becomes inexcitable near the anode when 

 the constant current is passed ; under similar conditions the heart 

 is inhibited and voluntary muscle relaxed. The condition is 

 reversible, and in fact constitutes a typical local anaesthesia. 

 The essential basis of the effect appears to be an altered electrical 

 polarization of the cell-surface. Near the anode, where the 

 current enters the cell or irritable element, the normal outer 

 positivity of the semi-permeable plasma-membrane is increased. 

 Apparently this change renders the membrane irresponsive to 

 stimulation. Variations in the electrical polarization of the 

 plasma-membrane are in all probability constantly associated 

 with variations in irritability. The facts of electrotonus show 

 that such changes of polarization may profoundly alter the 



1 Cf. my discussion of this possibility in Amer. Journ. Physiol., 1913, Vol. 31, 

 pp. 284 seq. 



