When less than the whole of any tract of land shall be sold, the quantity sold shall be in a square form, as near as practicable, at the most northwesterly corner of the tract, and when less than the whole of any in-lot or out-lot of any city or town shall be sold, the part sold shall extend from the main or principal street, road or alley, forming the most convenient front to such lot, to the rear of such lot, and so as to bound the same by lines as nearly parallel with the outlines of such lot as practicable.

(RSMo 1939 § 11138)