370 CHAPTERS ON EVOLUTION. 



produced by the special creation of new species; these in turn 

 becoming extinct at the close of their particular epoch. Creation 

 and extinction, on this theory, were thus alternating processes ; the 

 death of the one set of organisms heralded the production of the 

 new and independent forms. Such a hypothesis, tenable enough, of 

 course, on the theory of " special creation," is diametrically opposed 

 to that of evolution. But the case for the latter hypothesis was soon 

 proved to be overwhelmingly strong when the facts relating to fossils 

 were more fully investigated. Thus, when it is clear that all the 

 forms represented as fossils in one series of rocks are not, as a rule, 

 completely absent from the succeeding epoch, but are often found 

 represented in the next period, the case for the " special creation " 

 of each new series of fossils becomes materially weakened. Fur- 

 thermore, just as lines of genetic relationship connect existing 

 animals and plants, so like relations may be traced between extinct 

 and fossil forms. Hence the theory that the fossil animals and plants 

 of each period must represent the more or less typical descendants 

 of the life of the preceding epoch, at once rises into the domain of 

 rational belief. If we can believe that each new period is thus 

 peopled by the descendants of the preceding epoch, and by the 

 actual survivals from that period, the case for evolution grows in 

 strength ; and this belief is exactly that which modern geological 

 science esteems to have been the true cause of the succession of life 

 through the changing aeons of the past. " If the doctrine of evolu- 

 tion is sound," says Professor Huxley, " one of its immediate 

 consequences clearly is, that the present distribution of life upon the 

 globe is the product of two factors, the one being the distribution 

 which obtained in the immediately preceding epoch, and the other 

 the character and extent of the changes which have taken place in 

 physical geography between the one epoch and the other ; or, to put 

 the matter in another way, the Fauna and Flora of any given area, in 

 any given epoch, can consist only of such forms of life as are directly 

 descended from those which constituted the Fauna and Flora of the 

 same area in the immediately preceding epoch, unless the physical 

 geography (under which I include climatal conditions) of the area 

 has been so altered as to give rise to immigration of living forms 

 from some other area." 



The succession of life thus described offers convincing proofs of 

 the correctness of the evolutionist's views, and these proofs will be 

 presently considered. The nature and influence of the breaks or 

 u blank periods " of Mr. Darwin, which exist between the series, 

 remain, however, for primary notice. The geologist finds ample 

 cause in his study of the rock-masses to assume that the periods of 

 time which have elapsed between the end of one epoch and the 

 beginning of the next, have been of immense duration. That these 



