118 EVOLUTION 



causally relate them in a direct way to pe- 

 culiarities in habits or surroundings; they 

 are often distinct at birth or even hinted jat 

 before birth; they are rarely alike even among 

 forms whose conditions of life are uniform. 

 They are in many cases, if not always ^ t.r an i s- 

 missibls. They form, the raw material of 

 evolution. 



DARWIN'S POSITION IN REGARD TO VARIA- 

 TIONS. ODar^in recognized two kinds of 

 hereditary variations, in addition to those 

 extrinsic changes which we now call modi- 

 fications. In the first place he recognized 

 large "singly variatigfls^nr " sports J^j 

 and r^plf, in 



^ences fro^n thp tvpp of thg spraiW In the 

 second place he recognized slight "individ- 

 ual variations/' wMch are practically u^i- 



Q1 1 1 4- f\\ i ci f\ i c i* Tn <Tm g ri TT> ry /^riilri TT*f\fn "P> Q T*oyi "F 

 Hilling illhl MJ^MI^IIIM^ i it*ju IAI.HH JI.II^IL, 



brother from brother, cousin from cousin. 

 of t^*** kiVHi? of varf Q *"s wftffi 



and 



the direct result of environmental and 

 functional peculiarities. These correspond to 

 what we now call modifications, and.. jt_ 



1>n flim ' r 



Leaving-aside the question of the possible 



