164 MAN, THE ANIMAL 



through routes that have been In existence In the 

 nervous system of vertebrate animals since at 

 least the Devonian Geological epoch, a period of 

 time which must be estimated as not less than 

 several million years. One cannot help wonder- 

 ing what the effect would be if man's cerebrum 

 were In direct connection with his several sense 

 organs and direct instead of second hand Informa- 

 tion were received by It. In this connection let 

 me quote from one of the foremost neurologists. 



"The new brain, with its functions of correla- 

 tion. Is really as old, so far as Its beginnings are 

 concerned, as the old brain; but, whereas the latter 

 attains Its full development as a reflex and instinct- 

 ive apparatus In the lower mammals, the former 

 continues to Increase In size and Importance and it 

 is still increasing in the civilized human races of 

 to-day. 



"The kangaroo Is one of the lowest types of 

 mammals. A kangaroo with a body weight of 

 100 pounds has a brain weighing a little less than 

 2.5 ounces, or a ratio of brain to body weight of 

 1:711. In the human race this ratio Is 1:42. 

 The average brain weight of a European man is 

 about three pounds (1353 grams), the brain being 

 21 times as heavy as that of the kangaroo of about 

 the same body weight. This Increase In the 

 weight of the human brain Is almost entirely local- 

 ized in the association centers of the cerebral cor- 



