The topic of the paper under review is to discuss a practical approach to the approximate solution of singularly perturbed systems of d.e.'s of the type \((1)_{\mu} \dot x=f(x,y,t), \mu \dot y=g(x,y,t)\) with \(\mu\) being the small parameter. As usual it is assumed that the reduced system \((1)_ 0\) admits a reduced manifold of solutions with strong stability properties. In this case, as is well known, any solution of (1) essentially consists of two parts: fast motion (the boundary layer behaviour) and regular motion (close to the reduced manifold). The key point of the paper is the author's observation that numerical schemes, if applied to (1), require small steps even to compute the regular motion part, and not only in the boundary layer region. To fasten the numerical integration he therefore proposes to replace \((1)_{\mu}\) be a regular system of d.e.'s which is well suited to approximate regular motion parts.