This remark has no direct bearing upon the stems that underlie word formation. To a certain extent they are dependent upon morphological characteristics, at least in so far that non-existent grammatical categories must be supplied in other ways. When, for instance, some languages, like the Eskimo, lack those adverbial elements which correspond to our prepositions (in, out of, up, down, etc.), these must be supplied by special verbs which do not need to exist in languages that abound in locative verbal elements. On the whole, a certain correlation may be observed between the lexicographical and morphological aspects of a language. The more frequently “material” concepts (in Steinthal’s sense) are expressed by morphological devices, the more generalized are, on the whole, the word stems, and words are generally formed by limitation of these stems. When we find similar structure, we find, therefore, also a tendency towards the development of similar categories of stems. There are, however, others that are not so determined. It is, for instance, characteristic of many American languages that verbal ideas are expressed by different stems according to the form of the object in regard to which the verb predicates. This feature occurs particularly in verbs of existence and of motion, so that existence or motion of round, long, flat, etc., objects, are differentiated. This feature is prominent, among others, in Athapascan, Tlingit, Kwakiutl, and Sioux.
While I am not inclined to state categorically that the areas of distribution of phonetic phenomena, of morphological characteristics, and of groups based on similarities in vocabularies are absolutely distinct, I believe this question must be answered empirically before we can undertake to solve the general problem of the history of modern American languages. If it should prove true, as I believe it will, that all these different areas do not coincide, then the conclusion seems inevitable that the different languages must have exerted a far-reaching influence upon one another. If this point of view is correct, then we have to ask ourselves in how far the phenomena of acculturation extend also over the domain of languages.
Considering the conditions of life in primitive society, it is
