Source : Webster's Revised Unabridged Dictionary (1913)

Isatogen \I*sat"o*gen\, n. [Isatin + -gen.] (Chem.)
   A complex nitrogenous radical, {C8H4NO2}, regarded as the
   essential residue of a series of compounds, related to
   isatin, which easily pass by reduction to indigo blue. --
   {I*sat`o*gen"ic}, a.