Sec. 7. APPROPRIATIONS TO FUND OUT OF GENERAL FUNDS OF CITY. Any such city may make additional appropriations from time to time out of its general fund, or otherwise, into the said pension fund, and hereafter when any such city shall make any appropriations for pensions of city employees or place any money into any such account, the proportionate amount thereof shall be placed in the policemen's relief and retirement fund. Said pension fund may also be augmented as follows: By the giving of entertainments and benefit performances; by gifts or donations from any person, firm, or corporation; all rewards hereafter paid to or due individual members for, or on account of service rendered by them as members of the police department, shall be paid into such fund; and said pension fund shall also participate in funds otherwise provided or that shall hereafter be provided by law pertaining to police pensions of cities of the class herein provided for.