LIMITS OF COMPARATIVE PSYCHOLOGY 727 



Close observation and careful experiment have been devoted 

 to the study of insect behavior. Bethe alone argues energetically 

 that the movements of ants and of bees alike are unvarying re- 

 sponses to environment, usually to chemical stimuli. But the posi- 

 tion, clearly, is untenable. It is contradicted by such observations 

 as that of Forel * and others, that "bees, wasps, etc., can find their 

 way in flight through the air, notwithstanding wind and rain (and 

 hence under circumstances precluding the existence of any pos- 

 sible odoriferous trail)/' Loeb, also, offers a detailed observation 

 of a wasp which returned to its nest, carrying a caterpillar, and 

 therefore walking not flying. The wasp had flown from the nest, 

 so that it was not following any trail when it carried the caterpil- 

 lar to the nest. 2 



Advancing to the vertebrates, we find a number of experimental 

 observations. Triplitt has experimented on perch, repeating and 

 supplementing the classic experiment of Mobius on pike. He finds 

 that perch may learn both to avoid one side of an aquarium and 

 to inhibit the instinct to feed on smaller fish. 3 Yerkes has per- 

 formed the only experiments which I know on reptiles. 4 His 

 turtles learned to find their way through simple labyrinths, by 

 perpetuating successful movements even the chance move- 

 ment, unforeseen by the experimenter, of falling from the side of 

 an inclined plane, instead of crawling to the bottom of it. 



To the well-known experiments of Douglas Spaulding, Morgan, 

 and Thorndike on young chickens, Porter 5 has added a set of ex- 

 periments on the English sparrow. The investigators all agree 

 that birds learn through progressively varying reactions. Thorn- 

 dike's chicks learned to open the fastenings of boxes; Porter's 

 sparrows opened boxes and found their way through labyrinths; 

 and Morgan's chicks and pheasants were taught by experience to 

 avoid distasteful food. 



For the mammalia, Small 6 and Watson 7 and Miss Allen 8 have 

 proved that rodents learn to make their way through labyrinths 

 of varying difficulty; Morgan 9 and Mills, 10 Thorndike n and Hob- 



1 Ants and Some Other Insects, p. 18. Cf. Forel's ingenious experimental proof 

 of the memory of bees (not, as he thinks, of their inference), op. cit., pp. 22-27. 



2 Op. cit., pp. 224-227. 



* Amer. Jour, of Psychol. 1901, vol. xn, pp. 354 seq. 



4 Pop. Sri. Mo., 1901, vol. 58, pp. 519 seq. 



5 Amer. Jour, of Psychol. xv, pp. 313 seq., 1904. 



' The Psychic Development of the Young White Rat, Amer. Jour, of Psychol. 

 1899, vol. xi, pp. 80 seq. ; and Experimental Study of the Mental Processes of the 

 Rat, ibid., vol. xi, pp. 133 seq., vol. xii, pp. 206 seq. 



1 Animal Education : The Psychical Development of the White Rat, Correlated 

 with the Growth of Its Nervous System, University of Chicago Press, 1903. 



8 The Associative Processes of the Guinea-Pig, Journal of Comparative Neurology 

 and Psychology, 1904, vol. xiv, pp. 293 seq. 



9 An Introduction to Comparative Psychology, chaps. 5, 7, 12, 14, 16. 

 The Nature and Development of Animal Intelligence, pt. iii. 



11 Animal Intelligence, Psychological Review, Monograph Supplement, vin. 



