152 SCIENCE AND IMMORTALITY 



stimuli. Many so-called dead substances are as 

 sensitive to touch as the human skin, and as mobile 

 as the human muscles. We measure heat and 

 cold by the movements of the molecules of mercury 

 and alcohol ; and though we may not be able to see 

 the movement of a more solid metal under slight 

 changes of temperature, e par si muove. " The 

 sensitiveness of matter is such that a variation in 

 temperature of one millionth of a degree suffices 

 to modify its electric resistance in a fashion ap- 

 preciable by experiment." And metals are sensi- 

 tive not only to changes of temperature, but also 

 to electric changes. If a steel wire be touched with 

 the tip of a finger, its molecules are altered by an 

 electric current ; and if the faintest ray of light fall 

 upon a delicate platinum wire known as a bolometer^ 

 a change is at once produced in the molecular 

 structure of the wire. Even such a complex vital 

 phenomena as the electrical response of the retina 

 to light can be reproduced in an artificial metallic 

 retina, while in wireless telegraphy the response of 

 steel filings to Hertzian electric waves started 

 hundreds of miles away surely indicates a sensi- 

 tiveness which no living sense-organ can surpass. 



Matter must thus be admitted to be " endowed 

 with an unconscious sensibility which cannot be 

 approached by the conscious sensibility of any 

 living being." 



