526. Variation of terms of lease.

Where the terms of the relationship between the landlord and the tenant are altered by agreement, it is necessary to decide whether the alteration amounts to the creation of a new tenancy upon the altered terms, and thus of necessity the surrender by operation of law of the previous tenancy, or whether the alteration merely continues the previous tenancy in a varied form. Certain agreed alterations necessarily involve the surrender of the previous tenancy and its replacement by a new tenancy. The only way in which new land may be added to the demised premises is by the process