It is the policy of Congress to continue the agricultural research at State agricultural experiment stations which has been encouraged and supported by the Hatch Act of 1887 [7 U.S.C. 361a et seq.], the Adams Act of 1906, the Purnell Act of 1925, the Bankhead-Jones Act of 1935, and title I, section 9, of that Act as added by the Act of August 14, 1946, and Acts amendatory and supplementary thereto, and to promote the efficiency of such research by a codification and simplification of such laws. As used in this Act [7 U.S.C. 361a et seq.], the terms “State” or “States” are defined to include the several States (including the District of Columbia), Puerto Rico, Guam and the Virgin Islands. As used in this Act [7 U.S.C. 361a et seq.], the term “State agricultural experiment station” means a department which shall have been established, under direction of the college or university or agricultural departments of the college or university in each State in accordance with an Act approved July 2, 1862, (12 Stat. 503), entitled “An Act donating public lands to the several States and Territo­ries which may provide colleges for the benefit of agriculture and the mechanic arts” [7 U.S.C. 301 et seq.]; or such other substantially equivalent arrangements as any State shall determine.