It shall be unlawful for any telegraph company, telephone company, telegraph press association, railroad company, or any leased wire firm or private individual doing business in this state, and employing telegraphers for the purpose of transmitting telegraph dispatches for the general public, or any press association or private business, or in the operation of any railroad, to discriminate against any such telegrapher in its service or out of its service, or to blacklist or refuse employment to any telegrapher solely because of such telegrapher’s affiliation with or membership in any lawful organization or trade or labor union of telegraphers.