A solicitor for each judicial circuit or other territorial subdivision prescribed by the legislature, shall be elected by the qualified electors of those counties in such circuit or other territorial subdivision in which such solicitor prosecutes criminal cases, and such solicitor shall be learned in the law, and shall at the time of his election and during his continuance in office, reside in a county (in the circuit) in which he prosecutes criminal cases, or other territorial subdivision for which he is elected, and his term of office shall be for four years, and he shall receive no other compensation than a salary, to be prescribed by law, which shall not be increased during the term for which he was elected; provided, that this article shall not operate to abridge the term of any solicitor now in office; and, provided further, that the solicitors elected in the year nineteen hundred and four shall hold office for six years, and until their successors are elected and qualified; and, provided further, that the legislature may provide by law for the appointment by the governor or the election by the qualified electors of a county of a solicitor for any county.