v PROPOSED EXPERIMENTAL INVESTIGATION 235 



difficulty lies not in the experiment itself, but in 

 appreciating the results. Such results are not always 

 external and obvious ; many are internal and require 

 chemical and microscopical investigation in minute 

 details, and such differences in chemical constitu- 

 tion or in structure may have a great influence in the 

 struggle for life and operation of natural selection. 



In reference to use and disuse, experiments may be 

 made to diminish or suppress the activity and use of 

 some organ, by keeping plants or animals in such con- 

 ditions as to render some character useless. For 

 instance, one might try to obtain unscented or plain 

 flowers through artificial fecundation of all the flowers 

 of the same plant which require insect-intervention, 

 as it is supposed to have developed scent or colour in 

 view of attracting insects. Or again, place any animal 

 in such conditions as to render any one function use- 

 less ; or also, such as to render the development of 

 some organ or function of great use and necessity. 

 Experiments on the inheritance of mutilations may 

 be repeated at the same time : those which have been 

 already performed have not been successful nor 

 sufficient, although a priori it seems most likely that 

 the result will be exactly what it has been. For 

 such and other experiments bearing on the question, 

 intending experimenters may be referred to the essays 

 of Weismann, and W. P. Ball's Effects of Use and 



