By photo-transmutation of leptons we mean photon-lepton reactions of the following type: $γl_α\longrightarrow γl_β$ with $l_α\neq l_β$, occurring as a consequence of the lepton mass matrix changing its orientation (rotating) under changing scales. In this paper, we first discuss these reactions in general terms, then proceed to the calculation of their cross sections in two specific schemes, one within the framework of the conventional Standard Model, the other being the so-called Dualized Standard Model we ourselves advocate. Although the cross section obtained is generally small the calculation reveals certain special circumstances where these reactions may be accessible to experiment, for example with virtual photons in LEP for $γe \longrightarrow γτ$, and in BEPC for $γe \longrightarrow γμ$.

28 pages, Latex, 9 figures using eps and axodraw