The directors or governors of the association may from time to time make, alter and amend by-laws not inconsistent with the constitution of the United States or of the state, fixing or altering the number of its governors or directors for the management of its property and the regulation and government of its affairs and providing for the mode of filling vacancies in, and removing any member from, their number and prescribing qualifications for membership of the association and may appoint such agents and officers as shall in their judgment tend to promote or advance any purpose of the association, and may prescribe their respective duties.