The following persons may, at the discretion of such carrier, pass free of charge on all railroads and all other common carriers and may, at the discretion of such carrier, receive free tickets, passes and transportation from such carriers: employees of railroads and any and all other common carriers and their families; widows and dependent children of deceased employees; employees who have retired from active service, by reason of age or physical infirmities, and the wives and dependent children of the latter; officers or agents, surgeons, physicians and attorneys-at-law of any such railroads and other common carriers, and the immediate families of such persons; sheriffs; ministers of religion; traveling secretaries of the Young Men's Christian Association and the Young Women's Christian Association; inmates of hospitals and charitable and eleemosynary institutions and persons exclusively engaged in charitable and eleemosynary work; indigent, destitute and homeless persons; persons transported by charitable societies and hospitals and the necessary agents employed in such transportation; widows of soldiers who served during the War Between the States; inmates of a national home or state home for disabled volunteer soldiers and the sailors' and soldiers' homes, including those persons about to enter and those returning home after discharge and boards of managers of such homes; necessary caretakers of livestock, poultry and fruit; employees on sleeping cars, express cars and buses; linemen of telegraph and telephone companies; railway mail service employees; post-office inspectors; custom inspectors; immigration inspectors; newsboys on trains; baggage agents; witnesses attending any legal investigation or civil action in which such carrier is interested; persons injured in wrecks, when being transported from the place of injury to their homes or places of treatment and physicians and nurses attending such persons. Members of the Public Service Commission and its agents and employees, when traveling on official business, may pass free of charge on all the railroads and all other common carriers and may receive free tickets, passes and transportation from such carriers. Also, all such carriers may interchange passes, free tickets and transportation for the officers, agents and employees and their immediate families of all such carriers, and all such carriers may carry passengers free with the object of providing relief in cases of general epidemic, pestilence or other calamitous visitation. Editors and publishers of newspapers in Alabama may exchange with all railroads and all other common carriers in this state advertisements and space in the columns of their newspapers for mileage issued to such editors and publishers of newspapers.