Section 26. Subject to section twenty-seven the trustees may, in the name of and for the commonwealth, lease to any professor, instructor, teacher or employee of said university, or to any society, association or fraternity established thereat, land in Amherst or Hadley owned by the commonwealth, for the erection and maintenance of suitable dwellings thereon, at the sole expense of the lessee and for the lessee’s use and occupancy. Not more than one half an acre shall be so leased to any one such person or organization. Such leases shall contain such written terms, conditions, restrictions and reservations as the parties agree upon.