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. Conse-
quently, 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 build-
ing 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 unreason-
able 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