Whenever a rule or part of a rule is amended, the amendment shall be construed to merge into the original rule, become a part thereof, and replace the part amended. The remainder of the original rule and amendment shall be read together and viewed as one rule promulgated at one time; but the portions of the rule which were not altered by the amendment shall be construed as effective from the time of their original promulgation and the new provisions shall be construed as effective only from the date when the amendment became effective.