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carnivorous^ others graminivorous; some are viviparous, others 

 oviparous, &c. Yet there are certain other facts and orders of 

 facts which do not seem invariable. Such notably is the case 

 that, although parents produce offspring like themselves (this 

 being usually a recognized law), yet they never are absolutely 

 like them ; such differences as may appear in the offspring 

 being due, it is said in our ignorance, to the " laws of varia- 

 tion/^ This, however, is no explanation, but themselves are 

 orders of facts, and therefore we are once more driven back- 

 wards to find higher law or will. 



Here, then, we observe the diff'erence between the laws of 

 variation in the off^spring of living beings and laws governing 

 the lifeless physical phenomena of the world. The result of 

 the latter can be wdth tolerable or perfect accuracy predicted. 

 The resultant of laws of variation can never be foreseen. No 

 one can tell what are the preceding forces which give rise to 

 variation at all, nor in what direction the offspring may vary. 

 Here, then, is the occasion where chance is apt to find a 

 place in theories of specific origin ; but, as 1 have already 

 said, taking a long and consecutive view of nature's offspring 

 Ave are compelled to acknowledge the presence of an over-ruling 

 Law, though we cannot see it in the individual variations. 



Some of those forces which produce variation in the offspring 

 have been thought to be the exercise of muscular action, an 

 inherent principle of progression; while food and external con- 

 ditions acting upon the organs of reproduction is reservedly 

 suggested by Mr. Darwin, though he prefers to state more 

 emphatically that our ignorance of the laws of variation is 

 profound.'^ [Origin of Species j 4th edit., p. 195.) 



Now, as evolution hinges upon these so-called laws of varia- 

 tion, especial attention must be paid to them: for while we can 

 all recognize family likenesses, yet we can at once distinguish 

 any two members of a family from each other. This may be 

 a truism, but it lies at the bottom of evolution, for all that. 

 If, therefore, an offspring can be different, however slight, from 

 its parent, there are no a priori reasonable grounds for asserting 

 that the second generation may not differ from the first as much 

 as the first diff'ers from the original parents, until at last a being 

 may be produced so far different from the original parents, that 

 it would (if its history were unknown) be classed by a naturalist 

 as a different genus altogether. 



This, it will be remembered, has actually been done in the 

 case of pigeons, as described by Mr. Darwin in his Origin of 

 Species. On the other hand, some opponents of his views have 

 maintained that the power of variation is limited ; if so, the 



