Section 38. Signatures to initiative petitions need not be all on one paper. The papers constituting a petition shall be filed in the office of the city clerk, with the endorsement thereon of the names and addresses of three persons designated as filing the same, but all the papers need not be filed at the same time. The petition shall be considered filed whenever the designated persons notify the board in writing that the filing is complete. Before receiving such notice, the registrars of voters may, but shall not be required to, certify signatures on the papers already filed. With each signature to the petition shall be stated the place of residence of the signer, giving the street and number, if any.

Within five days after the filing of said petition the registrars of voters shall ascertain by what number of registered voters the petition is signed, and what percentage that number is of the total number of registered voters, and shall attach thereto their certificate showing the result of such examination.

The city clerk shall forthwith transmit the said certificate with the said petition to the city council or to the school committee, according as the petition is addressed, and at the same time shall send a copy of said certificate to one or more of the persons designated on the petition as filing the same.

When such certificate has been so transmitted, said petition shall be deemed to be valid unless written objections are made thereto by a registered voter of the city within forty-eight hours after such certification by filing such objections with the city council or the school committee, and a copy thereof with the registrars of voters or the board or commission having similar duties. Section seven of chapter fifty-five B shall apply to such objections, and the board of registration of voters shall transmit a copy of its decision to the city council or school committee.