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its explanation wholly in the change of the concentration during the 
reaction. 
Here also Mr. Rererers is obliged, if he wishes to maintain the 
favourable influence, to admit an “invertible” noxious action, which 
levels that very influence. 
To be sure we should by no means wish to omit mentioning that 
under the greatest possible reserve Ernst gives an explanation for 
the occurrence of the optimum curve in absence of injury, where- 
by this curve is again represented as the resultant of a rising and 
a descending curve. But the factor rising with the temperature as 
well as that falling with it, would according to Ernst, be of quite 
another nature than the factors which play a part in the theory of 
Dovcraux-BLACKMAN. For the increasing of the reaction-velocity with 
rise of temperature must in his opinion be a consequence of the 
greater value of “absorption velocity” at higher temperature; the 
decrease should be ascribed to the reduction of the quantity of the 
gas absorbed by the platinum surface at such a temperature. Of 
the before mentioned tune factor there is no question here 
whereas in  Duciaux-BLACKMAN’s theory the decrease should 
exclusively be ascribed to it. 
Referring to the preceding we still wish expressly to state that 
Mr. Rutgers is quite wrong in presuming that it would be our intention 
to contest BrLACKMAN's view, “that for explaining the reaction-velo- 
cities on botanical territory the physico-chemical laws must be the 
real base”. (See page 154 of his Dissertation). If one wishes for 
example, to compare our optimum curve, occurring when no noxious 
action is present, with the reaction curve for the process studied by 
Ernst, there is of course not the least objection. In our opinion it 
may be expected that specially the investigation of coagulation phe- 
nomena of proteids under the influence of temperature on one hand, 
and that of adsorption phenomena on the other, will give an expla- 
nation for the origin of such a curve. 
Summarising we come to the following conclusions : 
1. The theory of Dvcraux-BrLACKMAN to explain the occurrence 
of an optimum temperature is not accepted unmodified by Rereers. 
2. That it is confirmed by the facts, when modified as proposed, 
has not been proved by Rurenrs. 
3. Results found by us for physiological processes can only be 
brought into accordance with the modified theory by introducing 
three new hypotheses. For none of these efficacious arguments can 
be given. 
4, For the study of the relation between reaction velocity and 
