  We calculate the suppression in the rate at which two baryons in a nucleus
(viz., nucleons or $\Lambda$'s) convert to an H dibaryon, using an Isgur-Karl
wavefunction for quarks in the baryons and H, and a Bethe-Goldstone
wavefunction for the baryons in the nucleus. If $r_H \lsi 1/3~ r_N$, we find
$\tau_{A_{\Lambda\Lambda}\to A'_H}\gsi \tau_\Lambda$ and the observation of
$\Lambda$ decays from double-$\Lambda$ hypernuclei does not exclude the
existence of the H. If $m_H < 2 m_p$, nuclei are unstable but have very long
lifetimes. For reasonable values of $r_H$ and the nuclear wavefunction, the
lifetime can be long enough to evade anticipated SuperK limits $\tau_{A_{NN}\to
A'_H}\gsi {\rm few} 10^{29}$ yr, or short enough to be observed. An analysis of
SuperK data to look for this possibility should be undertaken.
