When one of the tenants in common, by mutual consent, has had the exclusive possession of a part of the estate and made improvements thereon, his share shall be assigned from or including such part. The value of the improvements made by a tenant in common shall be considered and the assignment of shares be made in conformity therewith. When any person shall have heretofore made or shall hereafter make improvements upon a part of any real estate with the consent of the owners thereof, or any of them, and such person shall have thereafter become a tenant in common of such real estate, his share shall be assigned from or including such part, and the value of the improvements so made shall be considered and the assignment of shares made in conformity therewith.