Introduction. 3 



Now in this opening chapter we shall have to do 

 merely with a setting forth of Darwin's opinion : 

 we are not considering how far that opinion ought 

 to be regarded as having been in any measure dis- 

 placed by the results of more recent progress. Such, 

 then, being the only matter which here concerns us, 

 I will supply a few brief quotations, to show how 

 unequivocally Darwin has stated his views. First, 

 we may take what he says upon the " Lamarckian 

 factors ^ ; " and next we may consider what he says 

 with regard to other factors, or, in general, upon 

 natural selection not being the sole cause of organic 

 evolution. 



" Changed habits produce an inherited effect, as in the period 

 of the flowering of plants when transported from one climate to 

 another. With animals the increased use or disuse of parts has 

 had a more marked influence "." 



" There can be no doubt, from the facts given in this chapter, 

 that extremely slight changes in the conditions of life sometimes, 

 probably often, act in a definite manner on our domesticated 

 productions ; and, as the action of changed conditions in 

 causing indefinite variability is accumulative, so it may be with 

 their definite action. Hence considerable and definite modifi- 

 cations of structure probably follow from altered conditions 

 acting during long series of generations '." 



" How, again, can we explain the inherited effects of the use 

 and disuse of particular organs ? The domesticated duck flies 



' So far as we shall be concerned with them throughout this trea- 

 tise, the "Lamarckian factors" consist in the supposed transmission 

 of acquired characters, whether the latter be due to the direct influence 

 of external conditions of life on the one hand, or to the inherited effects of 

 use and disuse on the other. For the phrase " inherited effects of use and 

 disuse," I shall frequently employ the term "nse-inheiitancc," which has 

 been coined by Mr. Piatt Ball as a more convenient expression, 



' Origin of Species, fith ed. p. 8. 



^ Variation Sac. 2nd ed. ii. p. 280, 



B a 



