94 BOTANICAL GAZETTE [AUGUST 
possible, the rapidity and degree of acclimation varies under most 
conditions directly with the rate of metabolism; consequently 
in the long run the susceptibility varies inversely as the metabolic 
rate. Within certain limits under these conditions, the higher the 
metabolic rate the longer life continues, because the higher the 
rate, the more rapid and complete the acclimation. Thus with 
the same differences in metabolic rate, the relative susceptibilities 
to high concentrations of a given agent are the inverse of those to 
very low concentrations of the same agent. 
These relations have been demonstrated for the cyanides, ethy! 
alcohol, ether and various other narcotics, acids and in marine forms 
for alkalies also, as well as for certain other substances and condi- 
tions, such as lack of oxygen, presence of carbon dioxide or other 
metabolic products in the medium, etc. It cannot be supposed 
that all these agents and conditions act on living protoplasm in the 
same way, but it is true that they all interfere with the activities 
of living protoplasm in some way. The general relation between 
susceptibility and metabolic rate is undoubtedly independent, at 
least to a large extent, of the particular method of action of a par- 
ticular agent or condition. With a certain rate of chemical reaction 
in protoplasm, certain conditions as regards enzymes, aggregation 
of colloids, permeability, etc., are in general correlated. The 
chemical reactions may be retarded or inhibited by means of changes 
in these various protoplasmic conditions, as well as by a direct 
chemical action; and since all these different factors in the activity 
of the protoplasm are correlated, its susceptibility to at least many, 
if not all inhibiting agents and conditions the effect of which is not 
instantaneous but progressive, must vary in general with its meta- 
bolic activity. If the inhibiting effect is so great that the proto- 
plasmic machine cannot adjust itself to the new conditions, the 
higher its rate of activity, the sooner it is brought to a standstill. 
But if the inhibiting effect is slight, the higher the rate, the more 
rapidly and completely adjustment occurs, because adjustment 
depends, at least in large part, on the activity of the protoplasmic 
machine, that is, upon metabolism. 
These relations between susceptibility and metabolic rate have 
been demonstrated in many different ways, and within certain 
