174 Inheritance of Acquired Characters 



by the selected transforming agent upon the whole organ- 

 ism, and our entire ignorance of the real nature of its 

 peculiar action, deprive these experiments of any value 

 as arguments against the theory of Weismann which 

 denies the inheritance of any peculiarly somatic char- 

 acters that have been acquired by means of local func- 

 tional adaptation to external influences that are very 

 definitely and clearly limited. 



Just as little valuable as proof against Weismann' s 

 theories were the . researches of Standfuss, Fischer, and 

 Bachmetjeff on the inheritance of changes in the color 

 design of butterflies' wings, when the pupae concerned 

 were placed in an unusually high or low temperature, 

 so that Weismann, as we shall see further in the next 

 chapter, could acknowledge the otherwise unimpeachable 

 results of these researches without thereby being com- 

 pelled to retrench his own theory. 



It would be best therefore to employ mechanical 

 means, and to produce changes whose mode and place 

 of working can be easily observed and definitely limited. 

 But amputations are to be excluded for the reasons 

 given, as are also sudden transformations, and so there 

 remains as the experiments best adapted for the final 

 decision of this disputed question, prolongation or fre- 

 quent repetition of the activity of certain organs or 

 definite parts of organs. 



We might suggest for example the artificial and 

 therefore extraordinarily frequent extension or contrac- 

 tion of the muscles of the fore or hind legs of a certain 

 animal, such as could be effected in little amphibia or 

 little mammals with the help of an especially devised 

 clock work. Prolonged traction on the tail of the rat 

 leading to its elongation and growth should be substituted 



