Turner, Homing of Ants. 369 



The first school, of which Bethe ('98, '00, '02) is the most noted 

 modern member, claims that these animals are mere machines 

 which respond to certain stimuli, always with the same fixed action 

 or set of actions. Some of these machines are, indeed, quite com- 

 plex; but so is the linotype. And as the linotype, in mechanical 

 response to a variety of definite stimuli, turns out line after line, 

 no two of which are exactly alike, just so the most complex activi- 

 ties of the invertebrates are but unconscious mechanical responses 

 to diverse stimuli. In other words, the life of these creatures is a 

 life of mechanical responses or tropisms. For them there is no 

 content of consciousness. Heliotropism, galvanotropism, stereo- 

 tropism, polarized trails, etc., explain all their behavior. They do 

 not learn. All reflexes may not be possible at birth, because the 

 physical mechanism is not yet perfected; but once the mechanism 

 has responded, thereafter under the same conditions, it always 

 responds to the same stimulus in the same way. 



The second school, to which I, hesitatingly, assign Pieron ('04, 

 '05), admits that reflex actions, some of which are connate and 

 some of which are deferred, do not fully explain the habits of ants. 

 According to them, the so-called instincts of these creatures are 

 decidedly plastic. They profit by experience; but not by associ- 

 ating present sensations with revived sensations, nor by inference, 

 nor by any of the higher forms of rational thought, but by what 

 Morgan ('00), Thorndike ('98), and others have called the 

 method of trial and error. 



The third school, to which belong Emery, Forel, Lubbock 

 ('81), Wasmann ('98, '00, '02) and others, holds that ants have 

 elementary feelings, ideas, and even what the English have called 

 a simple association of ideas, but that they do not have rational 

 thoughts and emotions. 



The fourth school, including L. Buchner ('80), Huber ('10), 

 MacCook, Romanes {'92) and others, insists that there is differ- 

 ence only in degree between human consciousness and the con- 

 sciousness of lower animals. 



To separate the third from the fourth school is to make a dis- 

 tinction which savors more of convenience than of scientific accu- 

 racy; for it is probably true that an idea differs from a product of 

 rational thought, not in kind, but in degree. 



A cknowiedgments. — The studies on the behavior of ants, of 

 which this contribution is the first fruit, were begun about five 



