THE TRIUMPH OF LIFE 



earth against which, in the free air, every poixi; 

 presses with its whole weight ! The solution was 

 obtained only at the cost of the centralization oi 

 the brain into a, for other purposes, senseless, 

 and in a true sense a "retrogressive" tail brain. 

 But it was not so fortunate in its permanent 

 regulation of the heating of this giant machine. 

 To be sure it was through the experiment of the 

 vertebrates that this regulation was fortunately 

 obtained in land animals. We ourselves possess 

 it, as all mammals and birds have it. With 

 them the warmth of the blood is independent of 

 the external temperature and remains at a fixed 

 point in all changes, like an eternally self -regu- 

 lated stove. In one way this had already been 

 attained ; indeed, it was attained in the midst of 

 the age of reptiles, but only with little animals, 

 the first tiny suggestion of mammals and birds. 

 How like an invention that is favorably ex- 

 pressed in a little model! With it came prog- 

 ress — at that time only with the very small. It 

 was only later that the maijimals arose from 

 these smallest forms to the elephant on the land 

 and in the water to the whale. But at that time 

 the colossal reptiles had not attained the sacred 

 fire of the new internal sun. During an exceed- 

 ingly long period of external sun they vegetated 

 like unconquerable feudal lords, but meanwhile 

 the real possessor, the thinking brain, lay in the 

 lazy hide. Then they broke down, incapable of 



