344 The Naturalist in La Plata. 



hand that; held the tail had been visible and in the 

 cage, the bites would undoubtedly have been inflicted 

 on it ; but no enemy was visible ; yet the fury and 

 impulse to attack an enemy was present in the 

 animals. In such circumstances, the excitement 

 must be discharged — the instinct obeyed, and in 

 the absence of any other object of attack the illusion 

 is produced and it discharges itself on the struggling 

 companion. It is sometimes seen in dogs, when 

 three or four or five are near together, that if one 

 suddenly utters a howl or cry of pain, when no man 

 is near it and no cause apparent, the others run to 

 it, and seeing nothing, turn round and attack each 

 other. Here the exciting cause — the cry for help — 

 is not strong enough to produce the illusion which 

 is sometimes fatal to the suffering member ; but 

 each dog mistakingly thinks that the others, or one 

 of the others, inflicted the injury, and his impulse is 

 to take the, part of the injured animal. If the cry 

 for help— caused perhap s by a sudden cramp or the 

 prick of a thorn — is not very sharp or intense, the 

 other dogs will not attack, but merely look and 

 growl at each other in a suspicious way. 



To go back to Azara's anecdote. Why, it may 

 be asked — and this question has been put to me in 

 conversation — if killing a distressed companion is 

 of no advantage to the race, and if something must 

 be attacked — why did not these rats in this instance 

 attack the cage they were shut in, and bite at the 

 woodwork and wires ? Or, in the case related by 

 Mr. Andrew Lang in Longman's Magazine some 

 time ago, in which the members of a herd of cattle 

 in Scotland turned with sudden amazing fury on 



