Further to carry out the purposes of this chapter the Secretary of Agriculture is authorized to issue to any qualified person, upon presentation of satisfactory evidence of competency, a license to sample cotton. Any such license may be suspended or revoked by the Secretary of Agriculture whenever he is satisfied that such licensee is incompetent or has knowingly or carelessly sampled cotton improperly, or has violated any provision of this chapter or the regulations thereunder so far as the same may relate to him, or has used his license, or allowed it to be used, for any improper purpose. The Secretary of Agriculture may prescribe by regulation the conditions under which licenses may be issued hereunder, and may require any licensed sampler to give bond for the faithful performance of his duties and for the protection of persons affected thereby and may prescribe the conditions under which cotton shall be sampled by licensed samplers for the purpose of classification by officers of the Department of Agriculture, or by licensed cotton classifiers.