38 THE GENESIS OF SPECIES. [CHAP. 



merit of the head, legs and antennae, are such as to render 

 them absolutely identical in appearance with dry sticks. 

 They hang loosely about shrubs in the forest, and have the 

 extraordinary habit of stretching out their legs unsymmetri- 

 cally, so as to render the deception more complete." Now 

 let us suppose that the ancestors of these various animals 

 were all destitute of the very special protections they at 

 present possess, as on the Darwinian hypothesis we must 

 do. Let it also be conceded that small deviations from the 

 antecedent colouring or form would tend to make some of 

 their ancestors escape destruction by causing them more or 

 less frequently to be passed over, or mistaken by their per- 

 secutors. Yet the deviation must, as the event has shown, 

 in each case be in some definite direction, whether it be 

 towards some other animal or plant, or towards some dead 

 or inorganic matter. But as, according to Mr. Darwin's 

 theory, there is a constant tendency to indefinite variation, 

 and as the minute incipient variations will be in all direc- 

 tions, they must tend to neutralize each other, and at first 

 to form such unstable modifications that it is difficult, if 

 not impossible, to see how such indefinite oscillations of 

 insignificant beginnings can ever build up a sufficiently 

 appreciable resemblance to a leaf, bamboo, or other object, 

 for " Natural Selection " to seize upon and perpetuate. This 

 difficulty is augmented when we consider a point to be 

 dwelt upon hereafter how necessary it is that many indi- 

 viduals should be similarly modified simultaneously. This 

 has been insisted on in an able article in the North British 

 Review for June 1867, p. 286, and the consideration of the 

 article has occasioned Mr. Darwin to make an important 

 modification in his views. 1 



1 "Origin of Species," 5th edit. p. 104. 



