4 A guardian cannot, however, be appointed for a particular matter or business, because his duties relate to the person, and not merely to a particular business or matter.
5 If a man appoints a guardian to his sons or daughters, he is held to have intended them also for such as may be afterborn, for the latter are included in the terms son and daughter. In the case of grandsons, a question may arise whether they are implicitly included in an appointment of guardians to sons; to which we reply, that they are included in an appointment of guardians if the term used is 'children,' but not if it is 'sons': for the words son and grandson have quite different meanings. Of course an appointment to afterborn children includes all children, and not sons only.
TITLE XV. OF THE STATUTORY GUARDIANSHIP OF AGNATES
In default of a testamentary guardian, the statute of the Twelve Tables assigns the guardianship to the nearest agnates, who are hence called statutory guardians.
1 Agnates are persons related to one another by males, that is, through their male ascendants; for instance, a brother by the same father, a brother's son, or such son's son, a father's brother, his son or son's son. But persons related only by blood through females are not agnates, but merely cognates. Thus the son of your father's sister is no agnate of yours, but merely your cognate, and vice versa; for children are member's of their father's family, and not of your mother's.
2 It was said that the statute confers the guardianship, in case of intestacy, on the nearest agnates; but by intestacy here must be understood not only complete intestacy of a person having power to appoint a testamentary guardian, but also the mere omission to make such appointment, and also the case of a person appointed testamentary guardian dying in the testator's lifetime.
3 Loss of status of any kind ordinarily extinguishes rights by agnation, for agnation is a title of civil law. Not every kind of loss of status, however, affects rights by cognation; because civil changes cannot affect rights annexed to a natural title to the same extent that they can affect those annexed to a civil one.