i8 THE MODERN STUDY OF ZOOLOGY 



supposed transformation of species ; they were 

 unable to show why species should become modified 

 into other species, and so, the onus probandi lying 

 with them, victory in the eyes of the world rested 

 with Cuvier. So complete was this victory con- 

 sidered at the time that for nearly thirty years 

 after his death Cuvier's authority was sufficient to 

 keep this new doctrine in abeyance. 



At length came the most eventful epoch in the 

 history of zoology, the simultaneous announcement 

 by two independent investigators, Charles Darwin 

 and Alfred Russel Wallace, of the doctrine of 

 Natural Selection, at the meeting of the Linnaean 

 Society on July 1st, 1858. This doctrine effected 

 for the animal world exactly what the geologist had 

 already done for the earth's crust ; it showed that 

 there are now in operation causes sufficient, given 

 time enough, to produce all the changes requisite 

 to convert the extinct fossil species into those now 

 living on the earth, causes that must have been in 

 operation since life first dawned on the earth, causes 

 that must inevitably have led to the passage of 

 species into species. 



In this way a complete and consistent theory of 

 the history of life on the earth was at length 

 obtained not only what had actually occurred, but 

 how and why it had occurred. And now at length 

 the true meaning of the laws of Cuvier regarding 

 the distribution of fossil remains was seen, those 

 laws which had led him to form his erroneous 

 theory of catastrophism. For instance, it was seen 

 now that the reason why the fossils of recent beds 



