DARWIN. 87 



fatal competition by having inhabited a protected 

 station. As buds give rise by growth to fresh buds, and 

 these, if vigorous, branch out and overtop on all sides 

 many a feebler branch, so by generation I believe it has 

 been with the great Tree of Life, which fills with its dead 

 and broken branches the crust of the earth, and covers 

 the surface with its ever- branching and beautiful ramifica- 

 tions." 



What may be the laws controlling or producing varia- 

 tion Darwin candidly tells us he does not know. Some 

 authors, he says, believe it to be as much the function 

 of the reproductive system to produce individual diffe- 

 rences, or very slight deviations of structure, as to make 

 the child like its parents. But we certainly do not know 

 the precise effect of any change of conditions, or what 

 changes maybe entailed in other parts of an organism by 

 given changes in one part. 1 



Why, if species are continually being modified, do we 

 not see multitudes of transitional forms around us ? How 

 can the elaborate structure and special habits of a bat 

 have been formed by the modification of some animal 

 of entirely different habits ? How can the marvellous 

 perfections of the human eye or that of one of the 

 higher animals be supposed to have arisen through 

 natural selection ? These questions Darwin answers 

 with powerful effect ; but for the details we must refer 

 the reader to the book itself. Incidentally he refers to 

 objections urged against the view that every detail of 



1 Mr. Romanes, in his paper on " Physiological Selection " 

 (Journal of the Linnean Society, Zoology, xix. 337-411), has 

 entered upon a most important discussion of this question. 



