4 BUKEAU OF AMEBIC AN ETHNOLOGY. 



III. Classification of languages — Continued. Page 



Influence of environment on language 53 



Influence of common psychic traits 56 



Uncertainty of definition of linguistic families 58 



IV. Linguistics and ethnology 59 



Practical need of linguistic studies for ethnological purposes 59 



Theoretical importance of linguistic studies 63 



Language a part of ethnological phenomena in general 63 



Language and thought 64 



Unconscious character of linguistic phenomena. 67 



V. Characteristics of American languages 74 



