488 THE GENERAL PRINCIPLES OE ZOOLOGY 



estimating the relation of cause and effect he arrives at the 

 proper method of meeting the new situation. Or, if reason 

 alone does not furnish a solution or appears impracticable, he 

 may pursue much the same method of experiment as any other 

 intelligent animal ; but, the result once obtained, he proceeds to 

 consider the causes which have brought it about, he resorts to 

 abstraction and generalization, and thus exhibits not only intelli- 

 gence but a power of reasoning. Whether any animal except 

 man possesses this faculty has often been asked, and our exact 

 knowledge of animal behavior is so slight as to make it diffi- 

 cult to replv. Experimental evidence is chiefly against the 

 theory that animals can reason in the strict sense of the word, 

 while simple intelligence appears to be amply sufficient to meet 

 all the usual though varied demands of their existence under 

 changing environments. The popular stories of reasoning in 

 animals are numerous, but on scientific examination most of 

 them will be found to be explicable on the simpler hypothesis. 



The manifestations of intelligence in animals are very 

 numerous, and some have been studied with great care. Among 

 the lower animals they are most conspicuous in the insects. 

 Examples are furnished by the military ants of the tropics, 

 which form veritable armies and wage war on neighboring 

 colonies ; by the harvesting ants of Texas as they meet the 

 varied conditions incident to clearing the ground about their 

 nests for the growth of the ant rice, which they harvest six 

 months later; by the methods employed by some of the wasps 

 in burying their prey, — they dig a hole in the ground and try to 

 put the spider which they have killed into it ; if the spider is 

 too large the hole is enlarged ; after burying it the wasp grasps 

 a stone in her jaws and with it pounds down the earth over the 

 hole. It is im possible here to enter into the details of these 

 various activities, but they all illustrate a remarkable interplay 

 of instinct and intelligence, the intelligence being manifested 

 along the line of the adaptability to new or untried conditions 

 and consisting chiefly in the ability to profit by chance successes. 



As a further illustration of this last point let us take an 

 instance from the behavior of the higher animals. Many d 

 readily teach themselves to open a door or gate by pressing the 

 latch. The casual observer remarks on the marvelous reasoning 





