xiv] ADAPTATION TO ENVIRONMENT 



under the influence of which it has been formed, and reveal the 

 climatic surroundings in which it was plasmated, and consequently 

 the region where it made its first appearance. 



A very grave objection, however, apparently arises to oppose the 

 adoption of so fascinating an hypothesis. 



Notwithstanding investigations and experiments of all kinds 

 it has been found that species at the present moment are little, 

 if at all, modified by the effects of their surroundings. The stimuli 

 have now but very slight power in the modification of individuals, 

 and adaptation to exceptional or abnormal conditions of existence 

 is not met with in that degree which would be required by my 

 hypothesis. Indeed, we may go still further and assert that living 

 beings vary very slightly or not at all at the present time, and that 

 they perish sooner than adapt themselves to new conditions of life. 

 A sufficient case to the point is that of all tropical, plants which are 

 cultivated in hothouses, which would infallibly perish if exposed, 

 even for a single day, to our outside air during winter. 



The Darwinian theory of evolution has caused the belief for the 

 time being that accidental variability (sport) exerted an all-important 

 and preponderating influence on the formation of new species, 

 and it has been thought that innate variability, helped by natural 

 and sexual selection, has been sufficient to produce the entire series 

 of organised forms which now exist or have existed. The Darwinian 

 theory does not, however, explain the reason of such an innate 

 tendency towards variation in organisms. 



Another argument strongly against the hypothesis that organisms 

 may have been modified by stimuli is found in the absolutely 

 negative results obtained by experiments. 



Rabbits have been kept and made to breed entirely in the dark 

 for many generations, and not the slightest trace of impaired 

 or modified vision has been detected in the later offspring. In the 

 same way mice have had their tails amputated, and rabbits their 

 ears clipped short from generation to generation, but never a mouse 

 has been born tailless, or a rabbit without ears. 



There are certain well-known mutilations and deformations 

 which have been practised on man himself for thousands of years, 

 and yet no indication of modification of the parts thus treated has 

 been observed. 



Moreover, if at the present time isolated individuals assume 

 some peculiar character or modify some organ, whether by use, or 

 as the result of the conditions in which they lived or were experi- 

 mentally subjected to, the acquired peculiarity or the modified 

 organ is not transmitted to their offspring. Thus the most essential 

 basis is wanting for the support of the theory of the response of 

 the organism to the sensations received, which ought to constitute 

 the basis of the theory of plasmation according to the environment. 



209 p 



