2 If heirs who are instituted in equal shares are reciprocally substituted to one another, and the shares which they are to have in the substitution are not specified, it is presumed (as was settled by a rescript of the Emperor Pius) that the testator intended them to take the same shares in the substitution as they took directly under the will.
3 If a third person is substituted to one heir who himself is substituted to his coheir, the Emperors Severus and Antoninus decided by rescript that this third person is entitled to the shares of both without distinction.
4 If a testator institutes another man's slave, supposing him to be an independent person, and substitutes Maevius in his place to meet the case of his not taking the inheritance, then, if the slave accepts by the order of his master, Maevius is entitled to a half. For, when applied to a person whom the testator knows to be in the power of another, the words 'if he shall not be my heir' are taken to mean 'if he shall neither be heir himself nor cause another to be heir'; but when applied to a person whom the testator supposes to be independent, they mean 'if he shall not acquire the inheritance either for himself, or for that person to whose power he shall subsequently become subject,' and this was decided by Tiberius Caesar in the case of his slave Parthenius.
TITLE XVI. OF PUPILLARY SUBSTITUTION
To children below the age of puberty and in the power of the testator, not only can such a substitute as we have described be appointed, that is, one who shall take on their failing to inherit, but also one who shall be their heir if, after inheriting, they die within the age of puberty; and this may be done in the following terms, 'Be my son Titius my heir; and if he does not become my heir, or, after becoming my heir, die before becoming his own master (that is, before reaching puberty), then be Seius my heir.' In which case, if the son fails to inherit, the substitute is the heir of the testator; but if the son, after inheriting, dies within the age of puberty, he is the heir of the son. For it is a rule of customary law, that when our children are too young to make wills for themselves, their parents may make them for them.
1 The reason of this rule has induced us to assert in our Code a constitution, providing that if a testator has children, grandchildren, or greatgrandchildren who are lunatics or idiots, he may, after the analogy of pupillary substitution, substitute certain definite persons to them, whatever their sex or the nearness of their relationship to him, and even though they have reached the age of puberty; provided always that on their recovering their faculties such substitution shall at once become void, exactly as pupillary substitution proper ceases to have any operation after the pupil has reached puberty.
2 Thus, in pupillary substitution effected in the form described, there are, so to speak, two wills, the father's and the son's, just as if the son had personally instituted an heir to himself; or rather, there is one will dealing with two distinct matters, that is, with two distinct inheritances.
3 If a testator be apprehensive that, after his own death, his son, while still a pupil, may be exposed to the danger of foul play, because another person is openly substituted to him, he ought to make the ordinary substitution openly, and in the earlier part of the testament, and write the other substitution, wherein a man is named heir on the succession and death of the pupil, separately on the lower part of the will; and this lower part he should tie with a separate cord and fasten with a separate seal, and direct in the earlier part of the will that it shall not be opened in the lifetime of the son before he attains the age of puberty. Of course a substitution to a son under the age of puberty is none the less valid because it is a integral part of the very will in which the testator has instituted him his heir, though such an open substitution may expose the pupil to the danger of foul play.
4 Not only when we leave our inheritance to children under the age of puberty can we make such a substitution, that if they accept the inheritance, and then die under that age, the substitute is their heir, but we can do it when we disinherit them, so that whatever the pupil acquires by way of inheritance, legacy or gift from his relatives or friends, will pass to the substitute. What has been said of substitution to children below the age of puberty, whether instituted or disinherited, is true also of substitution to afterborn children.