The Secretary of the Interior, or his designated representative, is authorized, under such regulations as the Secretary may prescribe, to make loans from the revolving fund established pursuant to the Acts of June 18, 1934 (48 Stat. 984) [25 U.S.C. 5101 et seq.], and June 26, 1936 (49 Stat. 1967), to tribes, bands, groups, and individual Indians, not otherwise eligible for loans under said Acts: Provided, That no portion of these funds shall be loaned to Indians of less than one-quarter Indian blood.