34 RADIOGENESIS IN EVOLUTION. 



of chromatic characteristics, but many critics are demon- 

 strating that these theories have been pushed to absurd 

 lengths. Here I may mention the work of Dewar and Finn* 

 and of Punnett. The very perfection of some mimetic 

 resemblances in butterflies, the simulation of fungoid 

 growths on a leaf pattern, for instance, is so unnecessary 

 and elaborate that it is difficult to account for on utilitarian 

 lines. There is a rich diversity of pattern and colour which 

 is a manifestation of radiogenetic variation. In passuig 

 we may note that such cases cannot be claimed as evidence 

 by the exponents of Vitalism. Kadiogenesis, when com- 

 ])ared with Orthogenesis, is at variance with any teleological 

 concei)tion. But I must not be tempted to dwell on this 

 point, more especially as I have dealt with it elsewhere. t 



The striking divergence of opinions among authorities 

 shows the difficulties attending the present study of vari- 

 ation and heredity. And here it seems to me that more 

 light can sometimes be shown by a .study of the past than 

 by an analysis of the present. May we not learn more, 

 both of laws and of dynamics, by collating evidence as to 

 the paths variations have gone, rather than by endeavour- 

 ing to trace the tracks they are taking I It has been aptly 

 .stated that man's outlook on the ])r()cesses of nature during 

 his life-time is com])arable to the momentary illumination 

 of a landscape during a lightning flash in a midnight storm. 

 It is therefore not to be wondered at, keen though our 

 observers be. that investigations in laboratories and ex- 

 periment grounds during the last half century have not 

 .satisfactorily elucidated what nature has accumulated 

 during long geological peiiods. 



Palaeontology is one of the youngest of sciences, but 

 it has not escaped many initial errors. Nor are we here 

 referring to such obviously incorrect views as the '" Cat- 

 astrophism " of Cuvier. The i)rinciple of some of the 

 older workers was to judge the complete biota of jiast 

 geological periods merely as preparatory stages for the life 

 of to-day. The assurance Avith which Haeckel di'ew up 

 genealogical trees (tentativelv. it is true) startled even 



*" The Making of Species,' John Lane, 1909. 



t" The Religion of a Naturalist," p. 38. (R.P.A.— Watts & Co.) 



