2 Causes and Course of Organic Evolution 



as proved by Mayer, were convertible into each other under 

 appropriate relations, and so "the transformability of energy" 

 was a fundamental law in physics. 



But the epoch-making discoveries of the past decade, and 

 especially the recognition of radio-active bodies, promise to 

 revolutionize many of the views that physicists, chemists, and 

 biologists have alike founded on in the past. So it can truly be 

 said that we live in a period of transition {1: 182), and that 

 no one can predict what the ultimate views — not to say estab- 

 lished facts — as to the constitution and relation of matter and 

 energy may be. 



The ancient opinion that a diffused and inert ether filled 

 the world and equally sidereal space was revived during the 

 past century, and it has been widely accepted that this ether 

 is a necessary constituent of the world's upbuild. It has been 

 viewed as composed of separate entities or units of extreme 

 elasticity. These units have been supposed to act as centers 

 round which charges of energy — of varying velocity according 

 to the substance studied — revolve at varying rates. So by 

 some the ether units were viewed as interpenetrating the atoms 

 of matter, and acting as vehicles for the transmission of energy 

 between the atoms. 



Le Bon {2: 13) says: "The ether is doubtless a mysterious 

 agent which we have not yet learned to isolate, but its reality 

 is manifest, since no phenomenon can be explained without 

 it. Its existence now seems to several physicists more certain 

 than even that of matter. It cannot be isolated, but it is 

 impossible to say it cannot be seen or touched. It is, on the 

 contrary, the substance we most often see and touch. When 

 a body radiates the heat which warms or burns us, what con- 

 stitutes tliis heat, if it be not the vibrations of the ether.^ When 

 we see a green landscape on the ground glass of a camera ob- 

 scura, what constitutes this image, if not the ether.'^*' 



But the past five years have brought to our notice some 

 remarkable and far-reaching views. From the researches of 

 the Curies (-5) and later of Rutherford and of Ramsay (4) into 

 the properties of radium and its direct relation to other bodies. 



