380 BOTANICAL GAZETTE [ DECEMBER 
expresses concisely recent views when he says (p. 165): “We 
may take it, then, that only that portion of a body is chemically 
active which is electrolytically active —that ionization is necessary 
for chemical activity just as it is necessary for electrolytic 
conductivity.” 
What applies to chemical activity must also apply to physi- 
ological activity, for in its ultimate analysis the latter is doubtless 
due to the former. Kahlenberg and True (’96) remark (p. 35) : 
‘It has always been taken as axiomatic that the physiological 
action of any substance is due to its chemical character.” 
The first work which deviated irreconcilably from the theory 
that all acids have ‘specific coefficients of affinity . . . . based 
on the fact that the relative affinities of different acids are the 
same, whatever the nature of the action by which they are com- 
pared” (Whetham, ’95, p. 162) was that of Levy (’95). It will 
be seen (line 6) that acetic, mono- and dichloracetic give coeffi- 
cients of activity which are in round numbers 200 per cent. in 
excess of that called for by the theory. The physiological 
activity of the acids towards phanerogams (Kahlenberg and 
True ’96) (line 7) is equally out of harmony with the theory, 
when we find the almost un-ionized HCN much more active 
than the ‘‘strong” mineral acids. The climax, however, 18 
reached in the data recorded on line 8, where we are dealing with 
concentrations which contain in many cases a very large propor 
tion of un-ionized molecules. : 
The chemical reactions involved in physiological investiga- 
tions are doubtless vastly more complex than in the case of the 
earlier studies recorded on lines 2-5. In the data recorded on 
lines 6-8, derived from the action of the acids on the more com 
plex carbon compounds, and the highly complex aldehydes, 
albuminoids, etc., found in the protoplasm of living cells, Lb 
surely find a great exception to the alleged law that the relative 
affinities of different acids are the same whatever the nature of the 
action by which they are compared. These affinities, indeed, appeat 
in some cases to be almost the converse of that required by !° 
theory above noted. 
