INTELLIGENCE OF ANIMALS. 349 



quired, as well as an equal recognition ot the 

 tones of voice by which approval, reprool or 

 anger are made known ; but, lacking the organs 

 of speech, they are debarred, and forever must 

 be, from any except the most limited interchange 

 of thought. For this reason, attentive study is 

 needed in ascertaining the extent to which they 

 comprehend and respond to the intelligence 

 which addresses them. 



In the case of wild or undomesticated animals 

 there is little opportunity for investigating this 

 interesting subject. We see the beaver build his 

 dam, and we understand the object so admira- 

 bly attained by his work. We know that the 

 elephant, to be taken in the pitfall, must see on 

 the earth that covers it the foot-prints of one of 

 his fellows, and we surmise the process of rea- 

 soning by which he concludes that he is safe in 

 venturing where another of his kind has trod- 

 den. We learn that the ostrich which in torrid 

 regions trusts to the heat of the sand for the 

 incubation of her eggs, will in a more temperate 

 latitude supply the heat which would else be 



