A glass tube provided with platinum electrodes, and containing some gas under very low tension, which becomes luminous when an electrical discharge is passed through it; -- so called from the name of a noted maker in germany. It is called also PlÜcker tube, from the German physicist who devised it. [1913 Webster]

geissler tube, n. a sealed tube of glass or quartz with a central constriction, filled with vapour for the production of a luminous electrical discharge.

Etymology:
H. Geissler, Ger. mechanic d. 1879

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