It was proposed that the COS payload should include an experiment to study cosmic γ-rays and one for cosmic X-rays. From a scientific point of view the association of these experiments is clearly valuable, the more so in view of Ogelmann's suggestion that the γ-rays observed by Clark, Garmire and Kranshaar and by Hutchinson represent the high energy extension of the spectra of galactic X-ray sources. It may, however, be argued that the X-ray sources can independently be studied and that, in any case, the most important sources near the galactic plane will be well enough known by the launch date of the COS satellite. This argument may not be valid in view of the observed variability of X-ray sources, but in any case a strong case can be made for the proposed kind of experiment.