  Reid's m'th-order generalized Ermakov systems of nonlinear coupling constant
alpha are equivalent to an integrable Emden-Fowler equation. The standard
Ermakov-Lewis invariant is discussed from this perspective, and a closed
formula for the invariant is obtained for the higher-order Reid systems (m\geq
3). We also discuss the parametric solutions of these systems of equations
through the integration of the Emden-Fowler equation and present an example of
a dynamical system for which the invariant is equivalent to the total energy
