The members and conditions of membership in the retirement system created by this act shall be as follows:
(a) All persons who shall hereafter become employees of the city prior to attaining the age of 45 years, shall, upon satisfactory completion of 3 months' service, become members of the retirement system herein created, as a condition of their employment; provided that all such persons shall submit to and pass the physical and mental examination required by the commission and shall furnish such evidence of good health, at said time, as the commission shall require; provided further, however, that the failure to pass the said physical and mental examination or failure to furnish satisfactory evidence of good health at such time shall not deprive the employee of his employment. The failure of any employee-member to comply with the rules and regulations prescribed by the commission, pursuant to this act, shall result in the suspension or termination of membership in, or benefits of, this retirement system as may be provided from time to time by the commission.