THE ORIGINS OF MIND II3 



centrate the light. Color change in the chameleon is an evo- 

 lutionary use of the response property where groups of 

 pigment under the skin are spread out or relaxed by muscles 

 in response to stimuli from the environment. 



From the property of muscle contraction, strangely 

 enough, nature has evolved on several occasions an electric 

 battery for the offensive and defensive activity of the or- 

 ganism. There are many variants on this invention, but the 

 best is in an electric eel of South America, a five-foot, fresh 

 water fish with a powerful battery running almost the full 

 length of the body on both sides. This fellow can deliver a 

 greater voltage than the domestic lighting system. He can 

 kill small animals or defend himself well against larger ones. 

 The battery is clearly a modified muscle and is an exploita- 

 tion of the fact that in normal muscle there is a slight electri- 

 cal charge at contraction. Even skin glands, as in the African 

 catfish, have been modified by nature into electric batteries, 

 again exploiting small electric potentials. 



Response, then, can and does occur in many ways in 

 organisms, but it is always traceable to the original primary 

 property in simple protoplasm. Furthermore, the exploita- 

 tion of this property is not exclusively an animal evolution. 

 In addition to the expected movement of roots and stem in 

 growth, and secretory activity in general, some plants show 

 very distinct "muscular activity." Mimosa, the "sensitive 

 plant," is one. The stimulus of mechanical shock on the 

 leaf of this plant causes the leaflets to fold together and the 

 whole leaf to bend downward. 



The property by which receptivity and response are 

 made to fit a given circumstance is coordination or correla- 

 tion. We see it best demonstrated in the highly developed 

 nervous systems of the higher animals. So incredibly com- 

 plex and talented are these higher systems that one might 

 suppose they could not have arisen from the simple correlat- 

 ing properties of protoplasm. They did, however, and we 

 have overwhelming evidences from living forms at all levels 



