The militia of the State consists of all able-bodied male citizens and all other able-bodied males who have declared their intention to become citizens of the United States, who are between the ages of eighteen and forty-five, and who are residents of the State, and of such other persons as may upon their own application be enlisted or commissioned therein pursuant to the provisions of this division, subject, however, to such exemptions as now exist or may be hereafter created by the laws of the United States or of this State.