108 THE WHENCE AND THE WHITHER OF MAN 



The animal emerges on land ; and, with a better sup- 

 ply of oxygen and less loss of heat, all the functions 

 are performed with the highest possible efficiency. 

 First, apparently, amphibia, then reptiles, and finally 

 mammals of enormous size and strength appeared. It 

 looked as if the earth were to be an arena where gigan- 

 tic beasts fought a never-ending battle of brute force. 

 But these great brutes reproduced slowly, had there- 

 fore little power of adaptation, were fitted to special 

 conditions, and when the conditions changed they dis- 

 appeared. The bird tried once more the experiment 

 of developing the locomotive powers to the highest 

 possible extent. It became a flying machine, and 

 every -organ was moulded to suit this life. Every 

 ounce of spare weight was thrown aside, the muscles 

 were wonderfully arranged and of the highest possible 

 efficiency. The body temperature is higher than that 

 of mammals. The whole organization is a physiologi- 

 cal high-pressure engine. The sense-organs are per- 

 haps the finest and keenest in the whole animal king- 

 dom. The brain is inferior only to that of mammals. 

 The experiment could not have been tried under more 

 favorable conditions ; it was not a failure, it certainly 

 was not a success when compared with that of mam- 

 mals. 



The possibilities of every system except one had 

 been practically exhausted. Only brain development 

 remained as the last hope of success. Here was an un- 

 tried line, and the mammals followed it. During the 

 short tertiary period the brain in many of their genera 

 seems to have increased tenfold. By the arboreal life 

 of the highest forms the hand is developed as the in- 

 strument of the thinking brain. The battle is begin- 



