278 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



But are there any facts ? 



At this point we come to speak about the second group 

 of Weismann's reasonings. He not only saw the difficulty 

 of understanding inheritance of acquired characters on the 

 principles of the science of his time, but he also criticised 

 the supposed facts ; and scarcely any of them stood the 

 test of his criticism. Indeed, it must fairly be granted that 

 not one case is known which really proves the inheritance 

 of acquired characters, and that injuries certainly are never 

 found to be inherited. In spite of that, I do not believe 

 that we are entitled to deny the possibility of the inherit- 

 ance of a certain group of acquired characters in an absolute 

 and dogmatic manner, for there are a few facts which seem 

 at least to tend in the direction of such an inheritance, 

 and which seem to show that it might be discovered perhaps 

 one day, if the experimental conditions were changed. 



I am not referring here to the few cases in which 



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bacteria were made colourless or non-virulent by outside 

 factors, or in which certain fungi were forced to permanent 

 agamic reproduction by abnormal external conditions and 

 were shown to retain their " acquired properties ' after 

 the external conditions had been restored. In these cases 

 only reproduction by simple division occurred, and that 

 does not imply the true problem of inheritance. Nor am I 

 referring to the few cases of non-adaptive " modifications ' 

 found by Standfuss and Fischer, in which butterflies that 

 had assumed an abnormal kind of pigmentation under the 

 influence of abnormal temperature acting upon the pupa, 

 were seen to form this same kind of pigmentation in the 

 next generation under normal conditions of temperature. 

 These cases, though important in themselves, are capable 



