rences of constitution. Thus, helium stars are found in special abundance near the Galaxy and it might be supposed that helium exists in greater proportion in that region, while most of the metals are lacking. An able discussion of this matter has been given by Sir Norman Lockyer, in his work on Inorganic Evolution, where it is shown that there is no localisation of the chemical elements so far as direction in space is concerned, and that although there are indications that particular types of stars do tend to congregate at distances peculiar to themselves, the condensation is by no means absolute. The occurrence of stars of the same type in widely separated parts of space, showing the same lines with similar intensities, is further regarded, with much justification, as evidence that not only do the stars contain the same elements, but contain them in identical proportions.
Spectroscopic investigation of the heavenly bodies has doubtless many wonderful revelations still in store, but it can scarcely be expected to lead to any greater generalisation than that which so clearly points to the chemical identity of the matter which builds up the countless diverse bodies of which the visible universe is composed.
London, Imperial College of Science.
