212 The Mechanistic Conception of Life 



The reader will notice that the aberrations produced at a 

 very low temperature (from 0° to —20° C.) are absolutely 

 identical with the aberrations produced by exposing the pupae 

 to extremely high temperatures (from 42° to 46° C.) • Moreover 

 the aberrations produced by a moderately low temperature 

 (from 0° to 10° C.) are dentical with the aberrations produced 

 by a moderately high temperature (from 36° to 41° C). 



From these observations Fischer concludes that it is errone- 

 ous to speak of a specific effect of high and of low temperatures, 

 but that there must be a common cause for the aberration found 

 at the high as well as at the low temperature limits. This cause 

 he seems to find in the inhibiting effects of extreme temperatures 

 upon development. 



If we try to analyze such results as Fischer's from a physico- 

 chemical point of view, we must realize that what we call life 

 consists of a series of chemical reactions, which are connected 

 in a catenary way; inasmuch as one reaction or group of reac- 

 tions (a) (e.g., hydrolyses) causes or furnishes the material for 

 a second reaction or group of reactions, (6) (e.g., oxidations). 

 We know that the temperature coefficient for physiological 

 processes varies slightly at various parts of the scale; as a rule 

 it is higher near 0° and lower near 30°. But we know also that 

 the temperature coefficients do not vary equally for the various 

 physiological processes. It is, therefore, to be expected that 

 the temperature coefficients for the group of reactions of the 

 type (a) will not be identical through the whole scale with the 

 temperature coefficients for the reactions of the type (6). If, 

 therefore, a certain substance is formed at the normal tempera- 

 ture of the animal in such quantities as are needed for the 

 catenary reaction (6), it is not to be expected that this same 

 perfect balance will be maintained for extremely high or 

 extremely low temperatures ; it is more probable that one group 

 of reactions will exceed the other and thus produce aberrant 



