Collectors shall attend all meetings for instruction to which they are summoned in writing by the Director. When a collector is unable to attend, he or she shall notify forthwith the Director stating the cause of such inability and, in his or her discretion, the Director may summon such collector to attend such other meeting as he or she may designate. Collectors attending such meetings shall receive therefor from the treasury of their municipality not less than $10.00 per day and their necessary expenses. (Amended 1959, No. 8, eff. Feb. 26, 1959; 1977, No. 105, § 14(a).)