Section 17
SEC. 17. Section fifty-two of said Act, as amended, is further amended to read as follows: "SEC. 52. The obligation to undergo military training shall begin with youth in school, commencing at the age of ten years, and shall extend through his schooling until he shall reach the age of twenty-one years when he shall become subject to service with the colors. If at eighteen to twenty-one years of age the youth is not attending any school or college he shall enter the Junior Reserve subject to the exemptions prescribed in section eighty-seven of this Act. The training which he may undergo prior to the calendar year in which he attains twenty-one years of age shall be termed Preparatory Military Training.' "All school girls shall receive such instruction and training as the Chief of Staff may deem necessary for auxiliary service. "All able-bodied male citizens between the ages of twenty years and fifty-one years, both inclusive, except, those specifically exempted, shall be classified as follows: "Trainees. - Those between the ages of twenty and twenty-one years who have been selected to receive military training. "First Reserve. - Those between the ages of twenty-two and thirty-one years, both inclusive, and including also all those who have completed trainee instruction or its equivalent even though they may not have attained the age of twenty-two. "Second Reserve. - Those betweai the ages of thirty-two years aid forty-one years, both inclusive. "Third Reserve. - Those between the ages of forty-two years end fifty-one years, both inclusive.