yed in building, and the object
of this provision is to avoid the necessity of having buildings pulled
down; but if through some cause or other they should be destroyed, the
owner of the materials, unless he has already sued for double value, may
bring a real action for recovery, or a personal action for production.

30 On the other hand, if one man builds a house on another's land with
his own materials, the house belongs to the owner of the land. In this
case, however, the right of the previous owner in the materials is
extinguished, because he is deemed to have voluntarily parted with them,
though only, of course, if he was aware that the land on which he was
building belonged to another man. Consequently, though the house should
be destroyed, he cannot claim the materials by real action. Of course,
if the builder of the house has possession of the land, and the owner of
the latter claims the house by real action, but refuses to pay for the
materials and the workmen's wages, he can be defeated by the plea of
fraud, provided the builder's possession is in good faith: for if he
knew that the land belonged to some one else it may be urged against him
that he was to blame for rashly building on land owned to his knowledge
by another man.

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