230 DARWIN AND PALEONTOLOGY 



the observation of slow origins of new characters. 

 It is well known that Darwin was a firm advo- 

 cate of the hypothesis of slow origins; this was, 

 indeed, consistent with his doctrine of evolution 

 by the adding up of favorable fluctuations. The 

 law of gradual appearance or origin of many new 

 characters in definite or determinate directions 

 from the very beginning I regard as the grandest 

 contribution which paleontology has made to 

 evolution. This law of gradual change in the 

 origin and development of single characters, 

 measurable only at long intervals of time, has 

 now come to rest on a vast number of observa- 

 tions ; it is the working basis of the science. Ver- 

 tebrate and invertebrate paleontologists search- 

 ing independently of each other on wholly differ- 

 ent kinds of animals have reached entirely sim- 

 ilar opinions. 



Mutations of Waagen. The first, I believe, 

 to express from observation the law of gradual 

 change was Waagen in 1868. The mutations 

 of Waagen ^ were originally distinguished by 

 him from the often more conspicuous contempo- 

 rary fluctuations by the fact that, although seen in 

 minute features, they are very constant and can 

 always be recognized again, but only in success- 

 ive geological levels, that is, at intervals of many 

 geologic years. Such gradations are observed 



^ Waagen, Wllhelm Heinrich: " Die Formenreihe des Ammonites 

 subradiatus," Benecke's Oeognostische Paldontologische Beitrage, 

 II, 1868, pp. 18S-86. 



