38 THE GENESIS OF SPECIES. [("hap. 



ijicnt of tlie lieaJ, le<,'S and anteniKT, are such as to ivndor 

 them absolutely identical in a})|)ein-ance with dry sticks. 

 They han^^ hjosely about shrul)s in the forest, and have tlie 

 extraordinary habit of stretchin<]: out their legs unsynnuetri- 

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

 let us su[)pose that the ancestors of these various animals 

 were all destitute of the very special protections they at 

 present possess, as on the Darwinian hy})othesis 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 frecjuently to be passed over, or mistaken by their per- 

 secutors. Yet the deviation must, as the event has sho.vn, 

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

 towards some other animal or plant, or towards some dead 

 or inorganic matter. lUit as, according to 'Slv. Darwin's 

 theory, there is a constant tendency to indefinite variation, 

 and as the minute incipient variations will be in all dircc' 

 tions, thev 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 ot 

 insignificant beginnings can ever build up a sufficiently 

 appreciable resemldance to a leaf, bandjoo, or other object, 

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

 difficulty is augmented whon 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 Britisli 

 Revieiv for June 1S(J7, ]>. 2.S(), and tlu; consideration of the 

 article has occasioned Mr. Darwin to make an important 

 modification in his views.^ 



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



