In any county in this state, where the inhabitants thereof have organized and established or may hereafter organize and establish a society for the encouragement and advancement of agriculture, manufactures and the mechanic arts and shall raise from said society, annually, the sum of 100 dollars or over, for the promotion of the above objects in said county, which fact shall be certified by the president and secretary of the society under oath, and a certificate thereof shall be filed with the clerk of the board of supervisors. The board of supervisors of said county at their annual session in each and every year, may, at their option, levy a tax of not more than 1/10 of 1 mill on the dollar, on the assessment roll of the county, which tax shall be collected and paid to the treasurer of the county in the same manner that other taxes are collected and paid: Provided, In any county where there is more than 1 agricultural society so reporting, the board may apportion such amount between such societies as they may deem just.