essary are such as a son or a
daughter, a grandchild by a son, and further similar lineal descendants,
provided that they are in the ancestor's power at the time of his
decease. To make a grandson or granddaughter a family heir it is,
however, not sufficient for them to be in the grandfather's power at
the moment of his decease: it is further requisite that their own father
shall, in the lifetime of the grandfather, have ceased to be the family
heir himself, whether by death or by any other mode of release from
power: for by this event the grandson and granddaughter succeed to the
place of their father. They are called family heirs, because they are
heirs of the house, and even in the lifetime of the parent are to a
certain extent deemed owners of the inheritance: wherefore in intestacy
the first right of succession belongs to the children. They are called
necessary heirs because they have no alternative, but, willing or
unwilling, both where there is a will and where there is not, they
become heirs. The praetor, however, permits them, if they wish, to
abstain from the inheritance, and leave the parent to become insolvent
rather than themselves.

3 Those who are not subject to the testator's power are called external
heirs. Thus children of ours who are not in our power, if instituted
heirs by us, are deemed external heirs; and children instituted by their
mother belong to this class, because women never have children in
their power. Slaves instituted heirs by their masters, and manumitted
subsequently to the execution of the will, belong to the same class.

4 It is necessary that external heirs should have testamentary capacity,
whether it is an independent person, or some one in his power, who is
instituted: and this capacity is required at two times; at the same time
of the making of the will, when, without it, the institution would be
void; and at the same time of the testator's decease, when, without
it, the institution would have no effect. Moreover, the instituted
heir ought to have this capacity also at the time when he accepts
the inheritance, whether he is instituted absolutely or subject to a
condition; and indeed it is especially at this time that his capacity to
take ought to be looked to. If, however, the instituted heir undergoes
a loss of status in the interval between the making of the will and
the testator's decease, or the satisfaction of the condition subject to
which he was instituted, he is not th