  The emission volume sizes of pions and Kaons, r_{\pi^\pm \pi^\pm} and
r_{K^\pm K^\pm}, measured in the hadronic Z^0 decays via the Bose-Einstein
Correlations (BEC), and the recent measurements of r_{\Lambda\Lambda} obtained
by through the Pauli exclusion principle are used to study the r dependence on
the hadron mass. A clear r_{\pi^\pm \pi^\pm} > r_{K^\pm K^\pm} > r_{\Lambda
\Lambda} hierarchy is observed which seems to disagree with the basic string
(LUND) model expectation. An adequate description of r(m) is obtained via the
Heisenberg uncertainty relations and also by Local Parton Hadron Duality
approach using a general QCD potential. These lead to a relation of the type
r(m) ~ Constant/sqrt{m}.
  The present lack of knowledge on the f_o(980) decay rate to the K^0\bar{K}^0
channel prohibits the use of the r_{K^0_SK^0_S} in the r(m) analysis. The use
of a generalised BEC and I-spin invariance, which predicts an BEC enhancement
also in the K^{\pm}K^0 and \pi^{\pm}\pi^0 systems, should in the future help to
include the r_{K^0_SK^0_S} in the r(m) analysis.
