Origin of Species Variorum

Comparison with 1869

conjecture by what transitions many organ could have arrived at its present state; yet, considering how small the proportion of living and known forms is to the extinct and unknown, ... I have been astonished how rarely an organ can be named, towards which no transitional grade is known to lead. It certainly is true, that new organs appearing as if specially created for some purpose, rarely or never appear suddenly in any class; as indeed is shown by that old canon in natural history of "Natura non facit saltum." We meet with this admission in the writings of almost every experienced naturalist; or as Milne Edwards has well expressed it, nature is prodigal in variety, but niggard in innovation. Why, on the theory of Creation, should this be so? Why should all the parts and organs of many independent beings, each supposed to have been separately created for its proper place in nature, be so invariably linked together by graduated steps? Why should not Nature have taken a leap from structure to structure? On the theory of natural selection, we can clearly understand why she should not; for natural selection can act only by taking advantage of slight successive variations; she can never take a leap, but must advance by the shortest and slowest steps.

Organs of little apparent Importance, as affected by Natural Selection.

As natural selection acts by life and death,— by the survival of the fittest, and by the destruction of the less well fitted individuals,—I have sometimes felt great difficulty in understanding the origin or formation of parts of little importance; almost as great, though of a very different kind, as in the case of the most perfect and complex organs.

conjecture by what transitions .. organs .. have arrived at their present state; yet, considering that the proportion of living and known forms ... is very small compared with the extinct and unknown forms, I have been astonished how rarely an organ can be named, towards which no transitional grade is known to lead. It certainly is true, that new organs very rarely or never suddenly appear in any class, as if created for some special purpose; as indeed is shown by that old, but somewhat exaggerated, canon in natural history of "Natura non facit saltum." We meet with this admission in the writings of almost every experienced naturalist; .. as Milne Edwards has well expressed it, Nature is prodigal in variety, but niggard in innovation. Why, on the theory of Creation, should there be so much variety and so little novelty? Why should all the parts and organs of many independent beings, each supposed to have been separately created for its proper place in nature, be so commonly linked together by graduated steps? Why should not Nature .. take a sudden leap from structure to structure? On the theory of natural selection, we can clearly understand why she should not; for natural selection .. acts only by taking advantage of slight successive variations; she can never take a sudden leap, but must advance by short and sure though slow steps.

Organs of little apparent Importance, as affected by Natural Selection.

As natural selection acts by life and death,—by .. the preservation of individuals with any favourable variation, and by the destruction of those with any unfavourable deviation of structure,—I have sometimes felt much difficulty in understanding the origin of simple parts, of which the importance does not seem sufficient to cause the preservation of successively varying individuals.