4 THE AGE OE THE EARTH 



run the i^auntlet of by far the greatest clangers which 

 beset the higher animals [and, it may be added, the 

 lower animals also] — the dangers of youth. Natural 

 Selection has alread)' pronounced a satisfactory verdict 

 upon the vast majorit)- of animals which have reached 

 maturity.' ^ 



But the criticism retains much force when applied to 

 another theory of evolution by the selection of large 

 and conspicuous variations, a theory which certain 

 writers have all alono- souorht to add to or substitute 

 for that of Darwin. Thus Huxlc)' from the ver)' first 

 considered that Darwin had burdened himself unneces- 

 saril)- in rejecting per saltiivi evolution so unreservedly.'^ 

 And recently this view has been revived by Bateson's 

 work on variation and by DeVries' researches on Oenothera 

 lamarckiaiia. I had at first intended to attempt a discus- 

 sion of this theory, together with Lord Salisbury's and 

 other objections which may be urged against it ; but the 

 more fully the two were considered, the more pressing 

 became the claims of the criticism alhided to at first — the 

 argument that the history of our planet does not allow 

 sufficient time for a process which all its advocates admit 

 to be extremely slow in its operation. I select this subject 

 because of its transcendent importance in relation to 

 organic evolution, and because I hope to show that the 

 naturalist has something of weight to contribute to 

 the controversy which has been waged intermittently 

 ever since Lord Kelvin's paper On Geoloo^ieal Tivie^ 

 appeared in 1868. It has been urged by the great 

 worker and teacher who occupied the Presidential Chair 

 of this Association when it last met in Liverpool that 

 biologists have no right to take part in this discussion. 

 In his Anniversary Address to the Geological Society in 

 1869 Huxley said : ' Biology takes her time from geology. 



' Poulton, Colours 0/ Animals, p. 308. 



' See his letter to Darwin, November 23, 1859 : Li/e and Lellers, vol. ii. 



■■ Trans. Geol. Soc, Glasgow, vol. iii. See also On the Age 0/ /he Su?is 

 Heat, IMacmillan, March, 1862 : reprinted as Appendix to Thomson and 

 Tait, Natural Philosophy, vol. i. part 2, second edition ; and On the 

 Secular Cooling 0/ the Earth, Royal Society of Edinburgh, 1862. 



