Let us begin by a survey of the different kinds of labour duties performed by the dependent holdings which clustered round the manorial centre. Foremost stands ploughing and the operations connected with it. The cultivation of the demesne soil of a manor depended largely on the help of the peasantry. By the side of the ploughs and plough-teams owned by the lord himself, the plough-teams of his villains are made to till his land, and manorial extents commonly mention that the demesne portion has to be cultivated by the help of village customs, 'cum consuetudinibus villae[573].' The duties of every householder in this respect are reckoned up in different ways. Sometimes every dependent plough has its number of acres assigned to it, and the joint owners of its team are left to settle between themselves the proportions in which they will have to co-operate for the performance of the duty[574]. In most cases the 'extent' fixes the amount due from each individual holder. For instance, every virgater is to plough one acre in every week. This can only mean that one acre of the lord's land is reckoned on every single virgate in one week, without any reference to the fact that only one part of the team is owned by the peasant. If, for example, there were four virgaters to share in the ownership of the plough, the expression under our notice would mean that every team has to plough four acres in the week[575]. But the ploughs may be small, or the virgaters exceptionally wealthy, and their compound plough team may have to cultivate only three acres or even less. The lord in this case reckons with labour-weeks and acres, not with teams and days-work. A third possibility would be to base the reckoning on the number of days which a team or a holder has to give to the lord[576]. A fourth, to lay on the imposition in one lump by requiring a certain number of acres to be tilled, or a certain number of days of ploughing[577]. It must be added, that the peasants have often to supplement their ploughing work by harrowing, according to one of these various systems of apportionment[578]. The duties here described present only a variation of the common 'week-work' of the peasant, its application to a certain kind of labour. They could on occasion be replaced by some other work[579], or the lord might lose them if the time assigned for them was quite unsuitable for work[580]. There is another form of ploughing called _gafol-earth_, which has no reference to any particular time-limits. A patch of the lord's land is assigned to the homage for cultivation, and every tenant gets his share in the work according to the size of his holding. Gafol-earth is not only ploughed but mostly sown by the peasantry[581].