120 ARE THE EFFECTS OF USE INHERITED? 



probable that he has no more definite or 

 " particulate " influence over the reproductive 

 elements within him than a mother over the 

 embryo or a vessel over its cargo. Parent and 

 offspring are like successive copies of books 

 printed from the same " type." A battered 

 letter in the " type " will display its effects in 

 both earlier and later copies alike, but a purely 

 extraneous or acquired flaw in the first copy js 

 not necessarily repeated in subsequent copies. Un- 

 like printer's type, however, the material source 

 of heredity is of a fluctuating nature, consisting 

 of competing elements derived from two parents 

 and from innumerable ancestors. 



Galton compares parent and child to suc- 

 cessive pendants on the same chain. Weismann 

 likens them to successive offshoots thrown up by 

 a long underground root or sucker. Such com- 

 parisons indicate the improbability of acquired 

 modifications being transmitted to offspring. 



