26 SCIENTIFIC THOUGHT 



nj ^Vt^ltV^lf <V)t\tt 44t/* t^/ rf**wW* MJHW /^t''T*^^. *fBfct. 



question, ' Why is this tree covered with these 

 leaves ? ' were to answer, ' Because the gardener 

 did not cut them away.' Of course that would 

 explain why there are no more leaves than those 

 actually there, but it would never account for the 

 existence and nature of the existing leaves as such. 

 Or [he concludes] do we in the least understand 

 why there are white bears in the Polar Regions if 

 we are told that bears of other color could not 

 survive ? "*4&jvta*? /v *rugjL tiSfj&fft^ 



Darwin himself recognized this fact, and in one 

 of his letters says, " Talking of ' Natural Selection'; 

 if I had to commence de novo, I would have used 

 * natural preservation.' "t 



" Natural Selection," says de Vries, J " acts as 

 a sieve ; it does not single out the best variations, 

 but it simply destroys the larger number of those 

 which are, from some cause or other, unfit for 

 their present environment. In this way it keeps 

 the strains up to the required standards, and in 

 special circumstances may even improve them." 



It cannot originate variations : that is the first 

 point to which we have to direct our attention. 

 And in the second place it cannot do every thing 

 in choosing and shaping the variations with which 

 it is confronted. What causes the variations ? 

 That is the kernel of the whole matter, and it is 

 one on which science at present, it must be con- 

 fessed, can sh^ed but little light. It is no good saying 

 that there is an inherent tendency in all living 



* Science and Philosophy of the Organism, vol. i, p. 262. 



j* Life and Letters , vol. ii, p. 346. 



Darwin and Modern Science^ p. 70. 



