THE THEORY OF ANESTHESIA. 



331 



and lipoid-solubility. Other physiological effects (e. g., mem- 

 brane-formation in sea-urchin eggs, 1 reversal of the sense of 

 heliotropism, sensitizing action, cytolytic action) show a similar 

 parallelism. The question of whether the particular physio- 

 logical effect under consideration is determined by one or the 

 other factor, or by the interaction of both, has to be decided by 

 further evidence. In favor of the view that lipoid-solubility 

 rather than surface-activity is the essential determining factor 

 in the action of lipoid-soluble narcotics, is the fact that the action 

 varies with temperature in the same direction as the oil-water 

 partition-coefficient. This is shown in a remarkable manner in 

 the following table from Hans Meyer. 2 The concentrations 

 required to narcotize tadpoles were determined at the two tem- 

 peratures 3 and 30 using (a) narcotics whose relative solubility 

 in oil decreases with rise in temperature, and (&) where it increases. 

 The critical anaesthetizing concentrations for the following six 

 anaesthetics are given in the table. 



TABLE III. 



In the first three compounds the relative lipoid-solubility 

 decreases and the narcotizing concentration increases with rise 

 of temperature; while with the others the conditions are reversed. 

 Thus simple cooling suffices to restore activity to tadpoles anaes- 

 thetized in chloral hydrate at 30. If adsorption under the 

 influence of surface-tension were the main factor in these effects, 

 such a change of narcotic power with temperature would be 

 inexplicable, since surface-tension is influenced in a totally 

 different manner by change of temperature. The fact that 



1 Cf. J. Loeb, "Artificial Parthenogenesis and Fertilization," University of 

 Chicago Press, 1913, Chapter 14. 



2 H. Meyer, Arch. f. exper. Path. u. Pharm., 1901, Vol. 46, p. 338. 



