i USE AND DISUSE 9 



which he desires to supplement it. It 

 seems unaccountable indeed that Mr. 

 Herbert Spencer should make so great 

 a fuss about so small a matter as the 

 effect of use and disuse of particular 

 organs as a separate and a newly re- 

 cognised factor in the development of 

 varieties. That persistent disuse of any 

 organ will occasion atrophy of the parts 

 concerned is surely one of the best 

 established of physiological facts. That 

 organs thus enfeebled are transmitted 

 by inheritance to offspring in a like con- 

 dition of functional and structural decline 

 is a correlated physiological doctrine not 

 generally disputed. The converse case 

 of increased strength and development 

 arising out of the habitual and healthy 

 use of special organs, and of the trans- 

 mission of these to offspring is a case 

 illustrated by many examples in the 

 breeding of domestic animals. I do not 



