266 GRAND STRATEGY OF EVOLUTION 



animals and plants, drawn from all quarters of the 

 globe; and from better agricultural returns. (2) To the 

 use of mineral fuels and water power. (3) To the 

 use of machinery. During the brief period of the nine- 

 teenth century, the resulting increase in man's construc- 

 tive power, and in his power of transportation, was far 

 greater than in all the preceding cultural eras, and is 

 without a parallel in any animal, for any length of time 

 whatsoever, in the whole history of evolution. The 

 chief creative value of this accomplishment lies in the 

 fact that, for the first time in evolution, it provided a 

 living organism with sufficient power for a continuous, 

 world-wide, vital circulation, comparable in its func- 

 tional and social significance with the initial circula- 

 tion of the blood in a growing embryo. 



3. The New Receptors and Perceptors. Sense 

 organs are living resonators, or receptors tuned to par- 

 ticular kinds of physical action. The range of action 

 to which they respond, that is, wave-length, energy, 

 and frequency, is in each organ very limited ; they are 

 either mute to actions outside that range, or destroyed 

 by them. 



In their respective functions and limitations, the 

 sense organs of man are much like those of other ani- 

 mals. In both cases, there is a vast world of nature- 

 action all about them, to which they do not, and cannot, 

 make an adaptive response. To them, this other and 

 greater world does not exist. 



Man alone is able to construct supplementary 

 sense organs, or perceptors, or measurers, of external 

 events; that is, he alone is able to select certain objects 

 which are highly sensitive to particular external acts, 

 or conditions, shield them from other influences, and 



