, which are often wide and conspicuous, render it difficult to trace anything of the nature of band absorption near 3885 for an
star.
(c) The Classification of
Stars.—Several lines of evidence have indicated that the classes into which the
stars have been divided are not physically homogeneous, and the problem of their classification is one of the future tasks of astrophysics. It is hoped that the writer can in the future make a more complete discussion of the question than is here desirable, and therefore the present treatment is to be considered merely suggestive and tentative. The material quoted is slight, and must be increased before conclusions can be justified.
It has been suggested[457] that a one-dimensional arrangement will not suffice for the classification of the