36 Instinct and Reason. 



intelligence and will ; " it receives sensations^ forms a notion of 

 their cause, reasons upon the ideas thus excited, perceives the end 

 to be attained, chooses the means of accomplishing it, and volun- 

 tarily puts these means into execution."* 



Such actions as these last are seen in their highest form in 

 man ; but they are not confined to him, for true reasoning pro- 

 cesses are also performed by many of the lower animals. There 

 is little doubt that this process is carried on by the brain, since 

 the size of that organ varies very much in proportion to the degree 

 of intelligence which the animal displays. Thus in man the 

 weight of the brain is one-thirtieth part of the weight of his whole 

 body, in the dog it is one hundred-and-twentieth part, while in the 

 ox, where the reasoning power is far inferior, it is one eight-hun- 

 dredth part only. Again, the brain of fishes rarely constitutes 

 more than one two-thousand part of the bulk of the whole body, 

 while in the invertebrate animals the brain, properly speaking, 

 does not exist at all. In the smaller birds and mammalia, as for 

 example the robin and the mouse, the bulk of the brain corres- 

 ponds more nearly with that of man in its proportion to the whole 

 body. It is, however, much less complicated in its mechanism, 

 and several organs invariably found in the human species are 

 entirely wanting in these animals. 



This variation is very much what we might have expected from 

 observation of the intellectual powers of the various animals. The 

 dog, which in proportion to the size of its body possesses the 

 largest brain next to man, is proverbially the most reasoning of the 

 lower animals. The innumerable instances adduced in proof of 

 this are too well known to require repetition. The power is best 

 exemplified in sheep-dogs, which can be taught not only to under- 

 stand and obey the orders given by their masters, but also to 

 judge for themselves with marvellous sagacity what is the best 

 course to pursue. I will relate one instance only. 



A butcher purchased a score of sheep from a large sheep farmer, 

 and begged the farmer to lend him his dog to take the sheep to 

 their destination, a distance of about ten miles. The farmer com- 

 plied, and added, " Send the dog off when you have done with 

 him, he will find his own way home." The journey was accom- 

 plished during the night, and the sheep were enclosed in the 

 butcher's paddock, but the dog could not be prevailed upon either 

 to return home or to enter the butcher's house. He lay in the 

 field near the sheep throughout the whole day, but during the 

 following night he managed to get them out of the paddock and 

 drove them all back to the farm of his master, where he made his 



• Carpenter, Animal Physiology, p. 514. 



