The municipal firemen’s relief and pension system, created, established and set forth in Chapter 41.18 RCW, is established in the city. All of the provisions, regulations and details of said chapters are by this reference incorporated herein. Any and all amendments of said chapters or of any section thereof hereafter made shall likewise by this reference be constituted amendments hereof, without the necessity of further adoption by the legislative authority of the city. (1961 code § 3.74.010.)