70. Accession to mortgaged property.

illustrations
(a) A mortgages to B a certain field bordering on a river. The field is increased by alluvion. For the purposes of his security, B is entitled to the increase.
(b) A mortgages a certain plot of building land to B and afterwards erects a house on the plot. For the purposes of his security, B is entitled to the house as well as the plot.