DARWIN AND PALEONTOLOGY 



tain other new characters, except in so far as 

 an evolutionary tendency once established in the 

 direction of brachycephaly or dohchocephaly is 

 apt to be pursued to its very hmits or extremes. 



Selection of minute variations. Not only is 

 paleontology not positively conclusive on the hy- 

 pothesis of selection of large variations, it has 

 nothing positive, but rather something negative 

 to say on the still more intimate or focal feature 

 of the Darwinian hypothesis that minute varia- 

 tions without direction in certain specific organs 

 are of survival or of elimination value. Certainly 

 appeal must be made to some other branch of 

 biology on this particular problem, if indeed it 

 is ever capable either of verification or of dis- 

 proof. Through paleontology we can neither 

 say that Darwin was right or wrong, because we 

 meet with certain peculiar barriers or limitations 

 of paleontological observation. Slight changes 

 of geological level may mark long periods of 

 time. The limitations are not solely due to rela- 

 tive rarity of contemporaneous or synchronous 

 material, because among invertebrates vast num- 

 bers of synchronous forms are sometimes brought 

 together so that minute variations may be read- 

 ily measured, but it is quite another matter to 

 prove through paleontology that such variations 

 are selected. It was Waagen's view that it is 

 not the variations but the less conspicuous muta- 

 tions which reappear in the next generation. 

 This question of the selection of minute varia- 



