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 
