The same language is spoken by the forms in which the luminous phenomena appear at the two poles of a Crookes tube. Fig. i on Plate A represents the whole phenomenon as far as such a diagram allows. Here we see on the positive side radial forms appear, on the negative side planar-spherical forms. As symbols of nature's script, these forms tell us that cosmic periphery and earthly centre stand in a polar relation to each other at the two ends of the tube. (Our optical studies will later show that the colours which appear at the anode and cathode are also in complete accord with this.)