Psychology of Animals. 205 



origin to instincts. The main drawback to this La- 

 marckian theory is the absence of evidence that acquired 

 characters may be inherited, but this difficulty was 

 usually slurred over until Weismann's essays made this 

 easy-going procedure impossible. 



Darwin recognized a twofold origin of instincts. On 

 the one hand, he admitted the possibility of the Lam- 

 arckian interpretation: Habits are estab- Darwin's 

 lished; cerebral changes ensue; it may be Position, 

 that the inheritance of these is the explanation of some 

 instincts. But it cannot be the explanation of all, he 

 said, for every one knows that the non-reproductive 

 worker-bees and worker-ants have instincts which are 

 quite foreign to their parents the males and queens. 

 Thus, there must be another explanation of instincts, 

 and this Darwin found in the action of natural selection 

 on congenital variations. 



One of the most prominent names in the history of 

 animal psychology is that of George John Romanes 

 (1848-1894), for, although there is legitimate The Work of 

 difference of opinion as to the cogency of Romanes, 

 some of his conclusions, he did more perhaps than any 

 other to raise the subject into dignity, and to place it 

 on a secure biological basis. He approached the study 

 from two sides, as a physiologist and as an evolutionist, 

 for his earlier work was concerned, on the one hand, 

 with the nervous and locomotor activities of medusae, 

 star-fishes, and sea-urchins; and on the other hand, 

 with a critical study of Darwinism. In his first pub- 

 lished work dealing with animal psychology (Animal 

 Intelligence, 1881) he set forth the reliable data, partly 

 from his own observation, largely from those of others, 

 and sifted the precise from the anecdotal. In his Mental 

 Evolution in Animals (1883) he developed his theory of 

 instinct, distinguishing primary instincts, which arise, 

 apart from intelligence, in the course of natural selec- 

 tion, and secondary instincts, which arise by the habitua- 

 tion and inheritance of activities originally intelligent. 

 In the same volume he began the comparison of the 

 mental life of man and animals, which he further devel- 

 oped in a third work on Mental Evolution in Man (1888). 



