the definition of the latter. However, the electromagnetic mass which causes the apparent mass, increases with velocity by a certain law. Therefore a certain relation must exist between the velocity and the ratio of mass to charge; as it was already said above, one can calculate both quantities by observing the deflections which were suffered by the rays under the influence of a magnet or an electric field; the study of these relations allows to separately determine the amount of both inertias. This result is totally surprising: *the real mass is equal to zero*. This conclusion is based, however, on the hypothesis mentioned before, but the agreement between the theoretical and the experimental curve is at least great enough, to make this hypothesis plausible.

Consequently, these negative electrons have no actual mass; if they still appear to be equipped with inertia, then this due to the fact that their velocity cannot be changed without a simultaneous disturbance of the luminiferous aether. Their apparent inertia is only borrowed, it doesn't belong to them, but to the aether. Yet, matter doesn't entirely consists of negative electrons; one can rather assume that there also exists real matter which possesses a certain inertia. There are rays also due to rain of projectiles, yet those projectiles carry positive charges with them: the canal-rays of Goldstein and the rays of radium belong to them; do those positive electrons also have no mass? This cannot be said, because they are much heavier than the negative electrons and are moving much slower.