§ 24 .] TOXIC ACTION AND CHEMICAL COMPOSITION. 33 
times strengthened. Thus, according to Stolnikow, dimethyl resorcin 
C 6 H 4 (OCH 3 ) 2 is more poisonous than resorcin C 6 H 4 (OH) 2 . Anisol 
C 6 H 5 OCH 3 , according to Loew, is more poisonous to algae, bacteria, and 
infusoria than phenol C 6 H 5 OH. On the other hand, the replacement 
by methyl of an atom of hydrogen in the aromatic oxyacids weakens 
their action; methyl salicylic acid 
salicylic acid C 6 H 4 
OH 
COOH. 
c 6 h 4 < 
O.CH, 
COOH 
is weaker than 
Arsen-methyl chloride As(CH 3 )C1 2 is strongly poisonous, but the 
introduction of a second methyl As(CH 3 ) 2 C1 makes a comparatively 
weak poison. 
These results admit, however, of a different interpretation, for 
Overton’s 1 researches show that the effect of narcotic substances depends 
on their greater or smaller power of penetrating into the nerve or other 
cells, and that this penetrating power has a direct relationship to the 
solubility of the substance in oil : those substances that are not soluble 
in oil do not enter into the nerve cells, those that are soluble easily 
penetrate. In the living cells there are not only oily matters, but 
also lecithin and cholesterin and their derivatives. The brain cells 
are especially rich in such ; to the fatty mixtures in the brain cells the 
name of brain lipoids has been given (AtVos 1 , fat). Alcohol or chloroform, 
after absorption by the blood, is practically in aqueous solution ; and 
when this aqueous solution is carried to the brain lipoids there is a 
partition of the alcohol between the lipoids and the serum, the value of 
. . .oil 
which is capable of being expressed by the coefficient -, the degree 
water 
of penetration being dependent on the magnitude of the resulting figure, 
which is obviously the larger the more soluble the substance is in oil. 
Limit of Concentra¬ 
tion necessary to pro¬ 
duce Narcosis in 
A-molecules per litre. 
Partition Coefficient, 
Olive Oil. 
Trional .... 
0-0018 
4-46 
Tetronal .... 
0-0013 
4-04 
Butyl chloral hydrate 
0-002 
1-59 
Triacetin . .. . . 
0-010 
0-30 
Diacetin .... 
0-015 
0-23 
Chloral hydrate 
0-02 
0-22 
Aethyl urethane 
0025 
0-14 
Monacetin 
0-0125 
0-06 
Methyl urethane 
0-40 
0-04 
1 Overton, Studien uber die Narkose, Jena, 1901. H. Meyer, “ Zur Theorie dor 
Alcohol Narkose,” Arch.f. exper. Pharmac., xlii. H. Meyer, *' Der Einfluss wechselnder 
Temperature auf Wirkungstarke u. Teilungscoefficient,” op. cit., xlvi. 
3 
