The ultimate fate of both tribes of red stars can only be conjectured. Most of the objects constituting them vary in brightness, some to the verge of periodical extinction; and variability may be a symptom of interior dilapidation. But the organization of such bodies is profoundly enigmatical. They are exceptionally remote, and offer slight holding-ground for inquiry. No indications have been gathered as to their density or intrinsic light-power. Very little is known about their movements. They rarely form binary combinations, and those that they do form are almost always relatively fixed. No red star travels in a computed orbit; only one, η Geminorum, occurs on the long list of spectroscopic binaries. The revolutions of this curious system ought to prove, when thoroughly investigated, replete with interest and instruction. Coupled stars present special opportunities to students of cosmogony. They are obviously contemporaries; they have started fair in the evolutionary race; identical influences have acted upon them; hence, differences in their standing can only result from dissimilarities in mass or composition. It is commonly taken for granted that a body containing less matter than its fellow must develop faster, and incur the final quenching sooner. But Sir William and Lady Huggins have adverted to the probability of the very opposite being the case. Powerful surface-gravity may, they consider, serve to hasten the transition from a Sirian to a solar spectrum; and we should then have giant suns like Capella, advanced in type while at a very early stage of condensation. This perhaps explains the remarkable spectral relations of contrasted stellar pairs. Always, so far as we yet know, the Sirian spectrum is yielded by the lesser star, the mass of which, judging by analogy, must be even smaller than would be indicated by the proportion of its faintness. It is true that the distribution of mass in binary systems is often widely different from what might have been anticipated. Certain purplish satellites, for instance, of undetermined spectral quality exercise a gravitative sway of surprising force. Some results of this kind lately obtained by Mr. Lewis and others are likely to prove of fundamental importance to theories of stellar evolution.