[ULPIANUS libro quarto disputationum. ] §28.6.24.prSi plures sint instituti ex diuersis partibus et omnes inuicem substituti, plerumque credendum et ex isdem partibus substitutos, ex quibus instituti sint, ut, si forte unus ex uncia, secundus ex octo, tertius ex quadrante sit institutus, repudiante tertio in nouem partes diuidatur quadrans feratque octo partes qui ex besse institutus fuerat, unam partem qui ex uncia scriptus est: nisi forte alia mens fuerit testatoris: quod uix credendum est, nisi euidenter fuerit expressum.
[ULPIANUS, Book 4 of Disputations.] If several persons are instituted for different portions and all are substituted mutually for one another, it should generally be believed that they are also substituted in the same portions in which they were instituted; so that, if for instance one is instituted for one-twelfth, a second for eight-twelfths, and a third for a quarter, upon the third rejecting his portion, the quarter is to be divided into nine parts, and the one who had been instituted for eight-twelfths is to take eight parts, and the one who was written for one-twelfth is to take one part: unless by chance the intention of the testator was otherwise; which is hardly to be believed, unless it has been clearly expressed.