Abstract
We prove that block spaces
defined on
{\mathbb{R}^{n}}
with an arbitrary Radon measure, which are known to be the preduals of Morrey spaces,
are closed under the first and the second complex interpolation method.
The proof of our main theorem uses the duality theorem in the complex interpolation method,
the complex interpolation of certain closed subspaces of Morrey spaces, a characterization of the preduals of block spaces, and
some formulas related to the Calderón product.