DARWIN'S THEORY OF EVOLUTION BY THE 

 SELECTION OF MINOR SALTATIONS 



HENRY FAIRFIELD OSBORK 



There is an opinion which is becoming more widely 

 prevalent daily that Charles Darwin's theory of selection 

 rests upon * ' fluctuations" which may not be heritable. 

 Nothing could be further from the facts. 1 



It is true that Darwin finally came to believe in the 

 inheritance of somatic modifications (in the modern sense 

 of bodily changes) caused by the direct action of environ- 

 ment as well as by habit (ontogeny), but in his original 

 (1859) and final (1872) opinion evolution was chiefly due 

 to the selection of heritable ''individual differences." 



Darwin's true meaning as to "individual differences" 

 is not to be found in his language, but in the cases he 

 cited ; he has been widely misunderstood 2 as believing in 

 continuous evolution whereas he chiefly believed in dis- 

 continuous evolution. 



Darwin's final opinion 3 may be cited with a transposi- 



1 De Vries is partly responsible for this general misunderstanding of 



pp. 431-451. 



that what we now call mutation had occasionally taken 



conviction that this process was exceptional and extra- 

 .t, as a rule, a new species originated by the gradual build- 

 i and even insignificant deviations from the average char- 

 species, which Si 1 iai ons ,»// /,•/,/,// - ' ' l\ 



I'hi.rs under Domestication/' Vol. 



