The definitions and general principles of the MK system given in the statement by Dr. Morgan, which Dr. McCarthy has read to you, are an expression of my views also.

It is mainly in specifying the MK domains that modifications are necessary for the cooler stars - and these for rather obvious reasons. For example, the spectral range has been extended to longer wavelengths, particularly for stars showing strong molecular bands. The lines and bands in the visual and far red regions are particularly useful in defining temperature and chemical composition, but the blue region remains important as having the features most sensitive to luminosity.