Any given nation usually has a large amount of homogeneity.
Whether this heterogeneity of structure is or is not consistent with homogeneity and continuity of substance is another question.
A limit to homogeneity of radiation is ultimately set by the so-called Doppler effect, which is the change of wave-length due to the translatory motion of the vibrating molecule from or towards the observer.
When the lines are obtained under circumstances which tend towards sharpness and homogeneity they are often found to possess complicated structures, single lines breaking up into two or more components of varying intensities.
Whereas during the 19th century states were being cut out to suit the existing distribution of language, in the 20th the tendency seems to be to avoid further rearrangement of boundaries, and to complete the homogeneity, thus far attained, by the artificial method of forcing reluctant populations to adopt the language of the predominant or governing race.
