788 
Though we admit the validity of Overton’s conception concerning © 
the elective permeability of the cell-wall, and the narcotic action of 
all kinds of compounds on the cell as a consequence of the presence 
of a “plasma skin-fatty substance’, conclusions about the behaviour 
of certain compounds towards the cell can be drawn from the value of 
the coefficient of distribution olive oil-water only if this “plasma-skin- 
fatty substance” is in exceedingly close relation with olive oil. 
About this “plasma skin-fatty substance” we know next to nothing, 
but it may be said with almost absolute certainty that — if it exists 
the chemical constitution will be entirely different from that of 
olive oil. But then determinations of the coefficient of distribution 
olive oil-water are worthless for a decision of permeability problems. 
This also appears already from the literature. Already on a cursory 
examination of the values published by Overton’) and Baum’), it 
is seen that the coefficient of distribution olive oil-water, and the 
strength of the narcotic action, indeed, in general vary in the same 
direction, but that mostly there is no question at all of a propor- 
tionality or even of an approximate agreement in the order of magni- 
tude. Besides we have been able to demonstrate in our first commu- 
nication that the coefficient of distribution olive oil- water can by 
no means serve to account for the assimilability or non-assimilability 
of unsaturated organic acids by moulds. 
Now the reason of this is clear: the solubility of a substance in 
olive oil is entirely independent, is by no means in any connection 
with the solubihty in any other fatty oil. 
4. QOverton*) has expressed the following opinion about the 
structure of the “plasma skin-fatty substance” : 
“Nach vielem Nachdenken neige ich immer mehr zu der Ver- 
mutung, dass das Cholesterin*) oder eine Cholesterinartige Ver- 
bindung (etwa eine Cholesterinester), resp. ein Gemisch solcher 
Verbindungen die imprägnierenden Substanzen sein dürften. Es 
wäre übrigens sehr wohl denkbar, dass Lecithin und in gewissen 
Fallen fettes Oel ebenfalls beteiligt sind, indem das Cholesterin 
demselben etwelchen Schutz vor der Verseifung gewähren diirfte”’. 
It need no argument that if really the plasma skin was soaked 
with such a cholesterine-lecithine mixture (called ‘“‘lipoid” by Overton), 
hence with substances absolutely different in chemical constitution 
from fatty oils, the coefficient of distribution olive oil-water would 
1) Cf. Studien über die Narkose (Jena 1901) pag. 100 et seq. 
) loc. cit. 
5) Vierteljahresschr. d. naturf. Gesellsch. Ziirich 44, 88 (1899). 
4) Also phytosterin etc. are, of course, included in this. 
