*The bu in early times represented 5 shaku square, or 25 square shaku (1 seki = 1 foot very nearly); but as the shaku (10 sun) then measured 2 sun (1 sun = 1.2 inch) more than the shaku of later ages, the modern bu (or tsubo) is a square of 6 shaku side, or 36 square shaku, though in actual dimensions the ancient and the modern are equal. The theory of distribution was that the produce of one tan served for food, while with the produce of the second tan the cost of clothes and so forth was defrayed. The Daika and Daiho legislators alike laid down the principle that rice-fields thus allotted should be held for a period of six years only, after which they were to revert to the Crown for redistribution, and various detailed regulations were compiled to meet contingencies that might arise in carrying out the system. But, of course, it proved quite unpracticable, and though that lesson obviously remained unlearned during the cycle that separated the Daika and the Daiho periods, there is good reason to think that these particular provisions of the land law (Den-ryo) soon became a dead letter. A different method was pursued, however, in the case of uplands (as distinguished from wet fields). These--called onchi*--were parcelled out among the families residing in a district, without distinction of age or sex, and were held in perpetuity, never reverting to the Crown unless a family became extinct. Such land might be bought or sold--except to a Buddhist temple--but its tenure was conditional upon planting from one hundred to three hundred mulberry trees (for purposes of sericulture) and from forty to one hundred lacquer trees, according to the grade of the tenant family. Ownership of building-land (takuchi) was equally in perpetuity, though its transfer required official approval, but dwellings or warehouses--which in Japan have always been regarded as distinct from the land on which they stand--might be disposed of at pleasure. It is not to be inferred from the above that all the land throughout the Empire was divided among the people. Considerable tracts were reserved for special purposes. Thus, in five home provinces (Go-Kinai) two tracts of seventy-five acres each were kept for the Court in Yamato and Settsu, and two tracts of thirty acres each in Kawachi and Yamashiro, such land being known as kwanden (official fields), and being under the direct control of the Imperial Household Department. *Called also yenchi--These uplands were regarded as of little value compared with rice-fields.