31 If Titius plants another man's shrub in land belonging to himself, the shrub will become his; and, conversely, if he plants his own shrub in the land of Maevius, it will belong to Maevius. In neither case, however, will the ownership be transferred until the shrub has taken root: for, until it has done this, it continues to belong to the original owner. So strict indeed is the rule that the ownership of the shrub is transferred from the moment it has taken root, that if a neighbour's tree grows so close to the land of Titius that the soil of the latter presses round it, whereby it drives its roots entirely into the same, we say the tree becomes the property of Titius, on the ground that it would be unreasonable to allow the owner of a tree to be a different person from the owner of the land in which it is rooted. Consequently, if a tree which grows on the boundaries of two estates drives its roots even partially into the neighbour's soil, it becomes the common property of the two landowners. 32 On the same principle corn is reckoned to become a part of the soil in which it is sown. But exactly as (according to what we said) a man who builds on another's land can defend himself by the plea of fraud when sued for the building by the owner of the land, so here too one who has in good faith and at his own expense put crops into another man's soil can shelter himself behind the same plea, if refused compensation for labour and outlay. 33 Writing again, even though it be in letters of gold, becomes a part of the paper or parchment, exactly as buildings and sown crops become part of the soil, and consequently if Titius writes a poem, or a history, or a speech on your paper and parchment, the whole will be held to belong to you, and not to Titius. But if you sue Titius to recover your books or parchments, and refuse to pay the value of the writing, he will be able to defend himself by the plea of fraud, provided that he obtained possession of the paper or parchment in good faith.