REMARKS ON THE CLASSICAL SIZE OF D-BRANES

We discuss different criteria for the ''classical size'' of extremal D irichlet p-branes in type-II supergravity. Using strong-weak coupling duality, we find that the size bf the strong-coupling region at the co re of the (p <3)-branes is always given by the asymptotic string scale , if measured in the weakly coupled dual string metric. We also point out how the eleven-dimensional Planck scale arises in the classical O- brane solution, and also the ten-dimensional Planck scale in the D-ins tanton solution.