185.36  Rights of police officers under former law.--The rights of police officers established or declared by any former provisions of this chapter shall not be impaired nor shall their benefits be reduced by virtue of any provisions of this chapter, provided however that no member may receive the benefits under the former chapter and also be entitled to receive the benefits under this chapter as amended in 1959. Unless an election in writing is made before January 1, 1960, to the board of trustees to remain under the provisions of the former chapter, it shall be conclusively presumed that the provisions of this chapter, as amended, will apply as to all police officers. Members who have retired under the former chapter prior to the enactment of the 1959 law shall continue to receive their benefits under the former chapter. Nothing in this law shall be construed as affecting benefits, due or to become due any police officer under a statutory pension plan.