10 [314] 



DARWIN ARD HUMBOLDT. 



that only a small fraction of the world 

 had been examined geologically, and 

 that even that fraction was still but 

 imperfectly known, he called atten- 

 tion to the history of geological dis- 

 covery as furnishing itself a strong ar- 

 gument against those who reasoned as 

 if the geological record were a full 

 chronicle of the history of life upon the 

 earth. There is a natural tendency 

 to look upon the horizon upon which 

 a fossil species first appears as mark- 

 ing its birth, and that on which it 

 finally disappears as indicating its 

 extinction. Darwin declared this 

 assumption to be " rash in the extreme. " 

 No palaeontologist or geologist will 

 now gainsay this assertion. And yet 

 how continually do Ave still hear men 

 talking of the stages of the geologi- 

 cal record, as if these were sharply 

 marked off everywhere by the first 

 appearance and final disappearance of 

 certain species. The boldness with 

 which Darwin challenged some of 

 these long-rooted beliefs is not less 

 conspicuous than the modesty and 

 deference with which his own sugges- 

 tions were always given. "It is 

 notorious," he remarked, "on what 

 excessively slight differences many 

 palaeontologists have founded their 

 species ; and they do this the more 

 readily if the specimens come from 

 different sub-stages of the same forma- 

 tion." 



Starting from this conception of 

 the nature of the geological record, 

 Darwin could show that the leading 

 facts made known by palaeontology 

 could be explained by his theory of 

 descent with modification through 

 natural selection. New species had 

 slowly come in, as old ones had slowly 

 died out. Once the thread of succes- 

 sion had been broken it was never 

 taken up again ; an extinct species or 

 group never reappeared, yet extinction 

 was a slow and unequal process, and 

 a few descendants of ancient types 

 might be found lingering in protect- 

 ed and isolated situations. " We can 

 understand how it is that all the 

 forms of life, ancient and recent, 

 make together one grand system ; for 



all are connected by generation. Front 

 the continued tendency to divergence, 

 the more ancient a form is, the more 

 generally it differs from those now 

 living. The inhabitants of each 

 successive period in the world's history 

 have beaten their predecessors in the 

 race for life, and are in so far higher 

 in the scale of nature; and this may 

 account for that vague, yet ill-de- 

 fined sentiment, felt by many palae- 

 ontologists, that organization on the 

 whole has progressed. If it should 

 hereafter be proved that ancient 

 animals resemble to a certain extent 

 the embryos of more recent animals of 

 the same class, this fact will be intel- 

 ligible." 



Again, what a flood of fresh light 

 was poured upon geological inquiry 

 by the two chapters on Geographical 

 Distribution in the Origin of Species f 

 A new field of research, or, at least, 

 one in which comparatively little had 

 been yet attempted, was there opened 

 out. The grouping of living organ- 

 isms over the globe was now seen to 

 have the most momentous geological 

 bearings. Every species of plant and 

 animal must have had a geological 

 history, and might be made to tell its 

 story of the changes of land and sea. 



In fine, the spirit of Mr. Darwin's 

 teaching may be traced all through 

 the literature of science, even in de- 

 partments which he never himself 

 entered. No branch of research has 

 benefited more from the infusion 

 of this spirit than geology. Time- 

 honored prejudices have been broken 

 down, theories that seemed the most 

 surely based have been reconsidered, 

 and, when found untenable, have been 

 boldly discarded. That the Present 

 must be taken as a guide to the Past, 

 has been more fearlessly asserted 

 than ever. And yet it has been re- 

 cognized that the present differs widely 

 from the past, that there has been a 

 progress everywhere, that Evolution 

 and not Uniformitarianism has been 

 the law by which geological history 

 has been governed. For the impetus 

 with which these views have been 

 advanced in every civilized country,, 



