THE PLAY OF ANIMALS. 181 



bert Spencer's view as it is set forth in the chapter 

 on " Sociality and Sympathy " of his Principles of Psy- 

 chology. He begins, it is true, with a purely associative 

 principle in seeking to show how all the members of a 

 herd of cattle often take to flight simultaneously, and 

 how through the frequent repetition of this a strong 

 association is gradually established between the signs of 

 fright in another and the consciousness of fear, so that 

 finally when only one animal perceives the danger, his 

 fright is communicated to all the others. From this he 

 goes on : " Evidently the process thus imitated must, 

 by inheritance of the effects of habit, furthered by sur- 

 vival of the fittest, render organic a quick and com- 

 plete sympathy of this simple kind. Eventually a mere 

 hearing of the sound of alarm peculiar to the species 

 will by itself arouse the emotion of alarm. For the 

 meaning of this sound becomes known, not only in the 

 way pointed out, but in another way. Each is con- 

 scious of the sound made by itself when in fear, and the 

 hearing of a like sound, tending to recall the sound made 

 by itself, tends to arouse the accompanying feeling. 

 Hence the panics so conspicuous among gregarious crea- 

 tures. Motions alone often suffice. A flock of birds, 

 toward which a man approaches, will quietly watch for 

 a while, but when one flies, those near it, excited by its 

 movement of escape, fly also, and in a moment the rest 

 are in the air. The same happens with sheep. Long 

 they stand stupidly gazing, but when one runs all run, 

 and so strong is the sympathetic tendency among them 

 that they will usually go through the same movement at 

 the same spot, leaping when there is nothing to leap 

 over." * 



* Herbert Spencer, The Principles of Psychology, p. 505. Audu- 

 bon's description of the flight of passenger pigeons forms a parallel 



