32O RALPH S. LILLIE. 



ever necessarily associated with a change in the irritability and 

 other vital properties of the tissue; in fact moderate cooling 

 may increase the irritability of nerve. Irritability and rate of 

 metabolic processes represent in fact two independent variables. 

 We infer that anaesthesia is not simply an expression of a decrease 

 in the velocity of certain chemical reactions, such as oxidations, 

 but that some other factor enters, probably physical in nature. 

 Certain other effects of temperature bear a closer resemblance 

 to true anaesthesia. Various irritable tissues become reversibly 

 insensitive at temperatures slightly below or above the normal 

 physiological range. Thus the frog's heart shows an accelerated 

 rate with rise of temperature up to 36 or 37; it then becomes 

 temporarily inactive and insensitive ("heat-standstill"), but 

 resumes beating if the temperature is lowered. Similarly the 

 musculature of tropical medusae becomes irresponsive at 40 

 and recovers on lowering the temperature. 1 This condition of 

 reversible heat-paralysis has certain suggestive resemblances to 

 anaesthesia. Cooling may produce a similar loss of sensitivity 

 in cells whose normal temperature is high, as those of tropical 

 marine animals 2 or warm-blooded vertebrates. Sensory nerve 

 endings, musculature, etc., lose sensitivity if cooled sufficiently, 

 and recover on warming. In these effects structural alterations 

 due to modification of the colloids of the cells (as gelation) are 

 probably concerned; and, as will be shown later, there are indica- 

 tions that similar changes form part of the essential basis of true 

 anaesthesia. The fact that changes of temperature may thus 

 alter the irritability of the tissue independently of their influence 

 on reaction-velocity as such, is highly important to the general 

 theory of narcosis; and it appears unfavorable to those theories 

 which refer anaesthesia to a simple change in the rate of chemical 

 processes like oxidation. Recent experiments by Loeb and 

 Wasteneys 3 on sea-urchin eggs illustrate this. They found that 

 during a condition of narcosis sufficient to arrest cell-division 

 completely, the rate of oxidation is lowered by only 10 per cent.; 



1 Cf. E. N. Harvey, Carnegie Institution Publications, No. 132, 1910, p. 32. 



2 Cf. A. G. Mayer, "Effects of Temperature upon Tropical Marine Animals," 

 Carnegie Institution Publications, No. 183, 1914, p. i. 



z journ. Biol. Chem., 1913, Vol. 14, p. 517; Biochem. Zeitschr., 1913, Vol. 56, 

 p. 295- 



