THE ACTIVE FORCES OF LIVING ORGANISMS 3 



closely riveted on the former that the latter has never 

 really emerged from the obscurity of the background. 

 The reason of this is not far to seek. Force is the j^^efaSor 

 one factor in the calculations of modern research 

 which escapes our ken, the impalpable element in all 

 our problems, the unknown quantity, the eternal X in 

 the algebra of science. It appears in many guises — 

 as wind, water, steam, light, heat, chemical energy, 

 molecular vibration, sound, magnetism, nervous im- 

 pulses, and electricity, now gathering its units into a 

 single wave, now scattering them over a broad expanse, 

 sometimes storing itself up with slow and steady pro- 

 gress, anon bursting forth into rapid and violent 

 shocks, transforming itself with surprising sudden- 

 ness, according to the conditions of the media through 

 which it passes, always in a sense active, always in- 

 visible, and yet never really lost. Assuredly what 

 little we know of such a phenomenon is sufficient to 

 make us attribute to it the greatest, most extensive, 

 most unforeseen powers, and to lead us to suspect its 

 action in those mysterious physiological processes 

 which without it are, and must, remain inscrutable, 

 impenetrable riddles. In an investigation such as 

 that which lies before us we shall see it in many 

 phases, carving, moulding matter, and being in turn 

 acted on, directed, modified. 



There is no more interesting theory with respect 

 to the constitution of matter than that of Sir W. 

 Thomson, which consists in regarding atoms as 

 little masses of ether always in motion, as differing, 



1—2 



