364 



SCIENTIFIC THOUGHT. 



ages with which geologists, since the time of Lyejl, have 

 been accustomed to reckon, are not supported by our 

 present knowledge of the periods during which the so- 

 called secular cooling of the earth has been going for- 

 ward the period which has elapsed since the " consis- 

 tentior status" of Leibniz set in. He has thus put 

 before natural philosophers a problem the reconcilia- 

 tion of the geological and the thermophysical record 

 in which the genetic view of nature must be greatly 

 interested. But even more important than all this is 

 the doctrine of the dissipation of energy, referred to in 



a doctrine of which 



53. 

 Dissipation 



of energy, the second chapter of this volum 



years has elapsed since the latter 

 part of the secondary period" 

 (' Origin of Species,' 1st ed., p. 287). 

 He shows that Hutton and the uni- 

 formitarians were misled by a be- 

 lief in the so-called stability of the 

 solar system, which took no notice 

 of the effect of tidal friction, nor 

 of the phenomena of radiation and 

 cooling in the past, still less of the 

 law of dissipation of energy, and 

 maintains that the modern ideas of 

 evolution are in a sense a return to 

 the older conceptions of Leibniz, 

 Newton, and other more recent 

 geologists (loc. cit., p. 111). Since 

 the subject was thus brought 

 prominently forward, astronomers, 

 physicists, and geologists have not 

 only as Huxley expected them to 

 do (see ' American Addresses,' 1886, 

 p. 93) adduced arguments in order 

 to arrive at an approximate idea 

 how long the earth may have been 

 able to maintain organic life, but 

 biologists have been induced to re- 

 vise the postulates of the extreme 

 almost infinite slowness, and of 

 the uniform continuity of organic- 

 changes, originally contained in the 

 Darwinian theory. The influence 

 of these researches upon biological 



and genetic reasoning has been to 

 emphasise the sudden changes, the 

 ruptures in the continuity of de- 

 velopment. In England the great 

 work of Mr William Bateson 

 (' Materials for the Study of Varia- 

 tions,' 1894) has familiarised us 

 with the idea of "Discontinuity" 

 in the origin of species. On the 

 Continent the rapid or even sud- 

 den appearance of variations is not 

 a new idea, though the original 

 suggestion of Maupertuis (1748), 

 which was taken up and elaborated 

 by Geoffroy St Hilaire (see Yves 

 Delage, ' L'Her&lite'. p. 291), was 

 forgotten. In quite recent years 

 the reconciliation of the " persist- 

 ence of species" with their "varia- 

 bility,"' and of the " geological :> 

 with the " biological " records, has 

 been much furthered by the theory 

 of " Mutation " of the celebrated 

 Dutch botanist de Vries. His view 

 is that " every species has it* be- 

 ginning and its end ; it behaves in 

 this way like an individual." He re- 

 fers to the experiments on heredity 

 and crossing of butterflies of Stand- 

 fuss, who has been led to maintain 

 the existence of sudden or ' ' ex- 

 plosive ' ; transformations ; and he 



