The amount necessary to provide the ordinary disability benefit shall be paid by the employer. Effective January 1, 1959, in respect to employees of a park district other than park policemen, who were transferred to the employment of a city by virtue of the “Exchange of Functions Act of 1957”, the city to which such employees are transferred shall pay the amount necessary for the purposes of the ordinary disability benefit.
     The board shall notify the board of park commissioners and the corporate authorities of the city to which employees of a park district have been transferred under the “Exchange of Functions Act of 1957” of the amount necessary for said purpose, and such amount, when approved by the board of park commissioners, or by the corporate authorities of the city in respect to such transferred employees, shall be included in the annual tax levy as provided in this Article.