Evidence for baryonium exchange in medium and high energy scattering

We review the prominent effects supposed to be associated with the exchange of baryonium Regge trajectories. The experimental presence of all expected effects leads us to suggest that the baryonium exchange mechanism is a correct phenomenological picture and that mesons with isospin 2 or $\text{3}\text{2}$ or with strangeness ?2, strongly coupled to the baryon-antibaryon channels, must be observed. An unexpected enhancement of the pure baryonium channel cross sections in the case of baryon decuplet production is pointed out. We also show that the old ?′ puzzle in π^?p → π⁰n seems to be solved by considering a recent generalization of the baryonium concept.