Mich. Comp. Laws § 81.8

Sec. 8. When the declaration of incorporation mentioned in the last preceding section shall be filed in the office of the secretary of state, as therein directed, the said village shall be deemed in law to be, and shall be, a city of the fourth class duly incorporated under and subject to the provisions of this act, by the name expressed in said declaration of incorporation; and the declaration of incorporation filed in the office of the secretary of state and in the office of the county clerk aforesaid, or the records thereof, or certified copies of such records shall be prima facie evidence of the due and legal incorporation of such village as a city of the fourth class under the provisions of this act.