Except as hereinafter provided, each college, community college, high school and each senior high school in this state having 100 or more students of 14 years of age or over and in which there is not maintained an R.O.T.C. unit shall establish a cadet company or companies under such rules and regulations as the governing body of the schools and the Adjutant General may prescribe, and any college, community college, high school or senior high school in the state having less than 100 of such students may establish a cadet company or companies. Said company or companies shall be of such strength as shall be prescribed by the Adjutant General. A cadet company or companies is not required to be established in a high school, college or community college unless a number of qualified students sufficient to constitute a company or companies of the strength prescribed by the Adjutant General voluntarily enroll therein.