304 The Influence of Environment 



TABLE XV 



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 

 (42° to 46° C). Moreover, the aberrations produced 

 by a moderately low temperature (from 0° to 10° C.) 

 are identical with the aberrations produced by a moder- 

 ately high temperature (36° to 41° C). 



From these observations Fischer concludes that it is 

 erroneous 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 analyse such results as Fischer's from a 



