330 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 11, NO. 14 



narcosis through the inhalation of air containing vapors of narcotics 

 did not take place however long such a mixture was breathed unless 

 the vapor pressure of the narcotic was above a definite threshold 

 value. 2^ The narcosis-producing vapor pressures run parallel in a 

 general way with the oil-water distribution coefficients of the different 



TABLE 1. — The Rei^ation of the Power of Certain Substances to Narcotize 



Tadpoles at Different Temperatures, to the Distribution Coefficients of 



These Substances between Water and Oil at These Temperatures 



volatile narcotics.-^ It is moreover curious to note that the effective 

 vapor tension of the narcotic in the blood of the narcotized animal is of 

 the same general order of magnitude, if calculated for the same body 

 temperature, in the animal series from the frog to the dog." 



Meyer and Overton assumed that since the narcotics are especially 

 soluble in the lipoids they will, of necessity, accumulate in those parts 

 of the body that are richest in lipoids. The nervous system is peculiarly 

 rich in lipoids. Hence these investigators explained in this manner 

 the accumulation of the lipoids in the nervous system and their selective 

 action upon it.'-^^ However, just as the lipoid theory of semi-per- 



2-' P. Bert. Sur la mortpar Vaction des melanges d'air et de vapeurs dechloroform. Compt. 

 rend. Soc. Biol. 35: 241. 1883. 



Methode d'anaesthesie par les melanges doses d'air et de vapeurs de chloroform. Ibid. 409. 

 Sur I'anaesthesie par l' ether. Ibid. 522. 



*^ E. Overton, op. cit. p. 85. 



" jj. Winterstein. Die Narkose (Julius Springer, Berlin, 1919), p. 33. 



28 Meyer and also Overton believed that the indifferent narcotics accumulated most in 

 the cortex because, according to the older analyses of the brain, the cortex is richest in 

 lipoids. Bethe, however, pointed out that, according to more recent analyses of Thudichum, 

 Koch and others, the white matter is far richer in lipoids than the gray; and Bethe dwelt 

 upon this as one of the objections to this hypothesis. However, there is no good reason to 

 suppose that interruption of the association tracts is not capable of producing narcosis as 

 readily as direct action on the cortical cells themselves. 



