384 On the Canal-Ray Group. . 
There arises the question as to whether the available material 
is sufficient to enable us to introduce a guiding and simplifying 
principle into the study o£ these complicated phenomena. In 
the literature of the subject, two views have been expressed 
regarding the nature of the discharge. According to one, the 
discharge and the radiation effects by which it is accompanied 
are regarded as a process taking place in the eether, the nature 
of which is not further particularized. According to the other, 
the discharge and radiation are identified with the motion of 
charged particles. At the present time the two views would 
appear to be capable of a certain amount of reconciliation, 
owing to the fact that many investigators are prepared to 
abandon the association of ordinary ponderable matter with 
" electrons," and to regard the masses in question as only 
apparent. In so far, therefore, as purely electrical processes 
may be regarded as actions taking place in the pether, a fusion 
of the two points of view does not appear improbable. The 
champions of the electron theory have gained heuristic aids 
by expressing the consequences of their hypothesis in mathe- 
matical form and attempting to verify the formulae by 
experiment. In this connexion it has appeared that in the 
case of the ordinary cathode rays the following may be re- 
garded as the determining variables : — the potential at which 
the rays are produced and propagated, the mass of the pro- 
jected particles, and the magnitude of their charges; the 
deflectibility of the rays under the action of electric or mag- 
netic fields increasing with the amount of charge, and de- 
creasing with increase of mass and potential. 
Possibly from the point of view of the electron theory the 
required general principle, primarily of heuristic importance, 
might be established were it possible to determine definitely 
the as yet doubtful direction of propagation of the Si-rays. 
Should this direction turn out to be — as is often assumed, 
though without proof — towards the cathode, it would afford a 
general view-point for certain actions of the canal-ray group. 
The disintegration of the cathode itself on the one hand, and 
the removal of the disintegration deposits by the canal rays 
already described on the other, might then be brought 
together under the general point of view according to which 
the Sj-rays and the canal rays cause removal of the metal 
wherever they terminate, while in connexion with the 
spreading of the Sj-rays in a direction away from the 
cathode, the rays would produce the same effect at their 
places of origin as do the canal rays at their terminations. 
Similar considerations may be applied to the fact that the 
canal rays excite luminescence in sodium, lithium, and 
