Lefevre — The Advance of Zoology in the Nineteenth Century. 89 



came upon the stage with startling abruptness ; and hence 

 the Darwinian Era is sharply marked off from the preceding 

 period. 



In the brief limits of this lecture it is impossible to give to 

 Darwin his true relative position or to adequately picture his 

 towering pre-eminence over all of his predecessors. 



During his long voyage as naturalist on the war-ship 

 " Beagle," detailed by the British Admiralty from 1831 to 

 1836 for nautical researches, Darwin had been deeply im- 

 pressed by the striking character of island faunas, especially 

 of the Galapagos Islands, and by the remarkable distribution 

 of Edentates in South America. Although on the voyage he 

 was a believer in special-creation, the peculiarities of distri- 

 bution which he had observed caused him to think much on 

 the subject of species, and he says he was haunted by the 

 problem of mutability. On his return he began to systemat- 

 ically collect from every available source facts concerning 

 variations of animals and plants under domestication and 

 in a state of nature, and to carefully search the litera- 

 ture of the subject. "In October, 1838," he says, "I 

 happened to read for amusement Malthus on Population, 

 and being well prepared to appreciate the struggle for 

 existence which everywhere goes on, from long continued 

 observation of habits of animals and plants, it at once struck 

 me that under these circumstances favorable variations would 

 tend to be preserved and unfavorable ones destroyed. The 

 result of this would be the formation of new species. Here, 

 then, I had at last got a theory by which to work." So 

 cautious was he, however, that he published nothing for many 

 years afterwards and it was not until 1842 that he even wrote 

 an outline of his view for his own satisfaction ; and this brief 

 abstract he enlarged two years later. At that time he wrote 

 his friend Hooker, " I have been ever since my return, en- 

 gaged in a very presumptuous work, and I know no one in- 

 dividual who would not say a very foolish one. I was so 

 struck with the distribution of the Galapagos organisms and 

 with the character of the American fossil mammif ers that I de- 

 termined to collect blindly every sort ©f fact which could bear 

 in any way on what are species. At last gleams of light have 



