42 A. E. HILTON ON THE NATURE OF LIVING ORGANISMS. 



The plasm thus defined is a colourless substance, of a jelly-like 

 consistency, neither solid nor fluid. It is about one-half water, 

 by volume or weight. Water, in fact, is the bed or frame of the 

 living machinery, in which the more solid constituents work. 

 In its entirety, plasm is a colloid. It is elastic and highly mobile ; 

 but, at the same time, it is tenacious, and not easily diffusible. 

 It is not soluble in an excess of water, and its power of absorbing 

 water is strictly limited ; but without a proper proportion of 

 water in its composition, the free action of the vital machinery 

 is impossible. 



Microscopists, examining plasm under high powers, have 

 fancied they could detect working parts of the living machinery. 

 Frothy, honeycomb, granular, thread-like appearances have been 

 described, on the supposition that these were characteristic of 

 pure plasm. Such ideas are no longer tenable. The appearances 

 may be those of plasm-products ; of the structure of plasm itself 

 they certainly are not, because it is purely a chemical substance, 

 actuated by chemical forces. Disappointing as it may be, we 

 must put aside our microscopes for the present, and pursue our 

 inquiry by the light of the new chemistry. 



Formerly, chemical science rested upon the fundamental con- 

 ceptions of molecules and atoms. Atoms were thought of as 

 ultimate particles of matter, indivisible and indestructible. Mole- 

 cules were groups of atoms, which could be broken up by chemical 

 processes; but of the affinities which determined the processes 

 no explanation could be given. The new chemistry, which 

 became established about ten years ago, retains the molecular 

 theoiy, and confirms the atomic structure of matter ; but atoms 

 are no longer regarded as ultimate or unalterable. Those attri- 

 butes have been transferred to electrons, the ultimate particles 

 of electricity, which pervades all substances, living and non-living. 

 Electrons are calculated to be at least one hundred thousand 

 times smaller than the atoms with which they are associated. 

 They are always in swift motion ; and the constitution of matter, 

 as now understood, presents to our imagination the surprising 

 spectacle of countless swarms of these tiny missiles, darting in 

 all directions in the spaces between the molecules, colliding, 



