pee 
LXXI. A Contribution to the Theories on Osmosis, Solubility, 
and Narcosis. By Professor I. TRAuBE, Berlin * 
ie a series of very able researches+ HE. Overton has deter- 
mined, by plasmolytiec and other methods, the velocity 
with which chemical compounds diffuse into the protoplast. 
Among the compounds which penetrate the cell-walls 
rapidly are the monovalent alcohols, aldehydes, ketones, 
aldoximes, ketoximes, mono- di- and trihalogen: car bohydrates, 
nitroalkyls, alkyl cyanides, the neutral esters of the inorganic 
and of many organic acids, aniline, pyridine, and the greater 
number of the alkaloids when in a free state, and the natural 
colouring-matters, ¢. e. those soluble in alcohol. 
The bivalent alcohols and the amides of the monovalent 
acids diffuse less rapidly ; whilst glycerol, urea, thio-urea, 
and erytritol diffuse more slowly “still. ‘The hexavalent 
aleohols, hexoses, and amido-acids scarcely diffuse at all ; 
while the cells are completely ¢mpervious to the salts of the 
pene inorganic acids, and to inorganic acids and bases. It 
s always observed that per meability increases in homologous 
Line: and also by the substitution of a hydrogen- atom by 
methyl, of methyl by ethyl, and so on. Thus there can be 
no question of any such sieving action as M. Traube supposes 
the membranes to exercise. 
Starting from a well-known experiment by Nernst f, and 
from the circumstance that, in general, compounds penetrate 
membranes the more rapidly, the more soluble they are in 
such substances as fats, cholesterine, lecithine, Ke. (7. e. the 
more lipoid-soluble they are), Overton evolves the theory that 
the magnitude of the distribution coefficient between fat, &c., on 
the one hand, and water on the other, determines the velocity of 
the osmosis. He assumes that, in the first instance, a dissolu- 
tion takes place in the fatty substance of the membrane at a 
velocity proportionate to this coefticient, and that thereupon 
the substance is passed on from the membrane to the interior 
of the cell. 
Again, Overton—and, independently, Hans Meyer §—draws 
attention to the notable circumstance, that all the reliable 
narcotics, anesthetics, and antipyretics are rapidly diffusing 
substances, and from this they deduce a theory, according to 
which the efficacy of a narcotic depends principally on its 
lipolidic solubility. These experiments, and above all Overton’s 
* Communicated by Prof. W. J. Pope, F.R.S. 
+ Overton, Vierteljahresschr. d. Naturf. Gesellsch. Ziirich, xl. p. 1 
(1895), and xliv. p- 88 (1899) ; Zeitschr. physik. Chem. xxii. p. 189 (1897). 
{ Nernst, Zeitschr. physik. Chem. vi. p. 37 (1890). 
§ Overton, Studien tiber die Narkose, Jena, Fischer (1901). 
