502 THE GENERAL PRINCIPLES OF ZOOLOGY 



between animals ; thus he considers the ape a degenerate man, 

 and points' out that by reasoning we should infer that they had 

 a common ancestor, which in one case gave rise to a being of a 

 higher order, the man, and in the other degenerated into a lower 

 type of organism, the ape. In the same way the ass is a de- 

 generate horse and the two had a similar origin. He hastens 

 to add, however: "But no; it is certain by revelation, that all 

 animals have shared the benefits of creation ; that the first pair 

 of each and every species has issued completely formed from 

 the hands of the Creator ; and we are forced to believe that 

 they were much the same as their descendants are to-day." It 

 thus appears that the facts of zoology led Buff on to a convic- 

 tion of the evolution of animals, while, on the other hand, he 

 felt bound by tradition to insist on special creation. Whether 

 he was serious in this latter point has been much discussed by 

 later writers. In other passages in his writings he shows 

 clearly that he recognized the principle of the struggle for exist- 

 ence and the elimination of the unfit, but without apparently 

 seeing the relation between these factors and the evolution of 

 animals. 



The naturalist who contributed the most to the theory of 

 evolution in the eighteenth century was Erasmus Darwin (i 731— 

 1802), grandfather of the celebrated author of the " Origin of 

 Species." He was a physician, a poet of considerable ability, 

 and a profound student of nature. His large work, the " Zoo- 

 nomia," a medico-philosophical treatise, was published in 1794. 

 He became a firm and outspoken believer in evolution, and in 

 this book brings forward a most logical series of arguments in 

 favor of it; and lest he should appear irreverent in preferring 

 this to the view of special creation he says, " For if we may 

 compare infinities, it would seem to require a greater infinity or 

 power to cause the causes of effects, than to cause the effects 

 themselves; that is, to establish the laws of Creation rather than 

 to directly create." He recognized the variation of organisms, 

 but instead of seeing the cause of these variations in environ- 

 ment, as Buff on did, he believed it to be inherent in the organism 

 itself, thus anticipating Lamarck's theory. He was fullv aware, 

 however, that his theory was incomplete, and believed that the 

 real cause of evolution was practically inconceivable. 





