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SCIENCE 



[N. S. Vol. XXX. No. 767 



names for some of the genera and species 

 which are commonly met with. Even 

 worse, the tentative arrangement of fossils 

 in "genetic series" has led to the inven- 

 tion of a multitude of terms which often 

 serve to give a semblance of scientific ex- 

 actitude to the purest guess-work, and 

 sometimes degenerate into a jargon which 

 is naturally repellent to an educated mind. 

 Nevertheless, I still hope to show that, with 

 all these difficulties, there is so much of 

 fundamental interest in the new work that 

 it is worth while to make an effort to ap- 

 preciate it. Geology and paleontology in 

 the past have furnished some of the grand- 

 est possible contributions to our knowledge 

 of the world of life; they have revealed 

 hidden meanings which no study of the 

 existing world could even suggest; and 

 they have started lines of inquiry which 

 the student of living animals and plants 

 alone would scarcely have suspected to be 

 profitable. The latest researches are the 

 logical continuation of this pioneer work 

 on a more extensive scale, and with greater 

 precision; and I am convinced that they 

 will continue to be as important a factor 

 in the progress of post-Darwinian biology 

 as were the older studies of fossils in the 

 philosophy of Cuvier, Brongniart and 

 Owen. 



In this connection it is necessary to com- 

 bat the mistaken popular belief that the 

 main object of studying fossils is to dis- 

 cover the "missing links" in the chain of 

 life. We are told that the idea of organic 

 evolution is not worthy of serious consider- 

 ation until these links, precise in character, 

 are forthcoming in all directions. More- 

 over the critics who express this opinion 

 are not satisfied to consider the simplest 

 cases, such as are afforded by some of the 

 lower grades of "shell-fish" which live to- 

 gether in immense numbers and have 

 limited power of locomotion. They de- 

 mand long series of exact links between the 



most complex skeletal frames of the back- 

 boned animals, which have extreme powers 

 of locomotion, are continually wandering, 

 and are rarely preserved as complete indi- 

 viduals when they are buried in rock. 

 They even expect continual discoveries of 

 links among the rarest of all fossils, those 

 of the higher apes and man. The geologist, 

 on the other hand, knowing well that he 

 must remain satisfied with a knowledge of 

 a few scattered episodes in the history of 

 life which are always revealed by the mer- 

 est accident, marvels that the discovery of 

 "missing links" is so constant a feature of 

 his work. He is convinced that, if circum- 

 stances were more favorable, he would be 

 able to satisfy the demand of the most ex- 

 acting critic. He has found enough con- 

 tinuous series among the moUusca, for 

 example, and so many suggestions of 

 equally gradual series among the higher 

 animals, that he does not hesitate to be- 

 lieve without further evidence in a process 

 of descent with modification. The mere 

 reader of books is often misled by the 

 vagaries of nomenclature to suppose that 

 the intervals between the links are greater 

 than in reality; but for the actual student 

 it is an every-day experience to find that 

 fossils of slightly different ages which he 

 once thought distinct are linked together 

 by a series of forms in which it is difficult 

 to discover the feeblest lines of demarca- 

 tion. He is therefore justified in proceed- 

 ing on the assumption that in all cases the 

 life of one geological period has passed by 

 a natural process of descent into that of the 

 next succeeding period; and, avoiding 

 genealogical guesswork which proves to be 

 more and more futile, he strives to obtain 

 a broad view of the series of changes which 

 have occurred, to distinguish between 

 those which denote progress and those 

 which lead to stagnation or extinction. 

 When the general features of organic evo- 

 lution are determined in this manner, it 



