Mass. Const. amend. art. XXII

[A census of the legal voters of each city and town, on the first day of May, shall be taken and returned into the office of the secretary of the commonwealth, on or before the last day of June, in the year one thousand eight hundred and fifty-seven; and a census of the inhabitants of each city and town, in the year one thousand eight hundred and sixty-five, and of every tenth year thereafter. In the census aforesaid, a special enumeration shall be made of the legal voters, and in each city said enumeration shall specify the number of such legal voters aforesaid, residing in each ward of such city. The enumeration aforesaid shall determine the apportionment of senators for the periods between the taking of the census. The senate shall consist of forty members. The general court shall, at its first session after each next preceding special enumeration, divide the commonwealth into forty districts of adjacent territory, each district to contain, as nearly as may be, an equal number of legal voters, according to the enumeration aforesaid: -- provided, however, no town or ward of a city shall be divided therefor; and such districts shall be formed, as nearly as may be, without uniting two counties, or parts of two or more counties, into one district. Each district shall elect one senator, who shall have been an inhabitant of this commonwealth five years at least immediately preceding his election, and at the time of his election shall be an inhabitant of the district for which he is chosen; and he shall cease to represent such senatorial district when he shall cease to be an inhabitant of the commonwealth.] [Not less than sixteen senators shall constitute a quorum for doing business; but a less number may organize temporarily, adjourn from day to day, and compel the attendance of absent members.]