Chap. XII. INHERITANCE. 473 



shall see in a future chapter that the long- continued use and 

 disuse of parts produces an inherited effect. Even those cha- 

 racters which are considered the most fluctuating, such as 

 colour, are with rare exceptions transmitted much more 

 forcibly than is generally supposed. The wonder, indeed, in 

 all cases is not that any character should be transmitted, but 

 that the power of inheritance should ever fail. The checks to 

 inheritance, as far as we know them, are, firstly, circumstances 

 hostile to the particular character in question ; secondly, con- 

 ditions of life incessantly inducing fresh variability ; and 

 lastly, the crossing of distinct varieties during some previous 

 generation, together with reversion or atavism — that is, the 

 tendency in the child to resemble its grand-parents or more 

 remote ancestors instead of its immediate parents. This latter 

 subject will be discussed in the following chapter. 



END OF VOL. I. 



