Embedding Deligne's category $\underset{‾}{\mathrm{R}\mathrm{e}}\mathrm{p}(S_t)$ in the Heisenberg category

We define a faithful linear monoidal functor from the partition category, and hence from Deligne’s category $\underset{‾}{\mathrm{R}\mathrm{e}}\mathrm{p}(S_t)$, to the Heisenberg category. We show that the induced map on Grothendieck rings is injective and corresponds to the Kronecker coproduct on symmetric functions.