6 THE EVOLUTION OF LIFE 
Later, the researches of Professor J. J]. Thomson ! 
and his school have shown that in the conduction of 
electricity through highly rarefied gases the particles 
shot out from the cathode (or negative pole), con- 
stituting the above-mentioned cathode rays, always 
carry an electrical charge identical with that conveyed 
by a single atom of hydrogen, though each particle 
in these cathode rays associated with this constant 
minimum charge has only about yoo of the bulk of 
the hydrogen atom ; and, more important still, that 
the particle is always of the same kind and size 
whatever the substance may be from which the 
cathode ray emanates. Such particles, all identical 
in mass and in the charge which they carry, are by 
Professor Thomson named “corpuscles,” though 
they are more commonly spoken of as “ electrons ”— 
a name previously suggested by Dr Johnstone Stoney, 
and indicative of the view now held by many that 
these elementary corpuscles are in reality electrical 
units. 
These “corpuscles ” or “electrons” are indeed 
now supposed to be the elementary units out of which 
the atoms of the various chemical elements are 
compounded—their number in each atom being very 
great, and increasing with each increase in the 
atomic weights of the several elements. 
Thus, while an atom of hydrogen whose atomic 
weight is very low (1) has been supposed to contain 
1000 of these corpuscles or negative electrons, an 
atom of mercury, with a very high atomic weight 
(200), has been supposed to contain 100,000 of such 
1 “ Conduction of Electricity through Gases,” 1903. 
