What led Humboldt toward the American tongues; progress of his studies; fundamental doctrine of his philosophy of language; his theory of the evolution of languages; opinion on American languages; his criterion of the relative perfection of languages; not abundance of forms, nor verbal richness; American tongues not degenerations; Humboldt’s classification of languages; psychological origin of Incorporation in language; its shortcomings; in simple sentences; in compound sentences; absence of true formal elements; the nature of the American verb. SOME CHARACTERISTICS OF AMERICAN LANGUAGES 349–389 Study of the human species on the geographic system; have American languages any common trait? Duponceau’s theory of polysynthesis; Humboldt on Polysynthesis and Incorporation; Francis Lieber on Holophrasis; Prof. Steinthal on the incorporative plan; Lucien Adam’s criticism of it; Prof. Müller’s inadequate statement; Major Powell’s omission to consider it; definitions of polysynthesis, incorporation and holophrasis; illustrations; critical application of the theory to the Othomi language; to the Bri-bri language; to the Tupi-Guarani dialects; to the Mutsun; conclusions; addendum; critique by M. Adam on this essay. THE EARLIEST FORM OF HUMAN SPEECH AS REVEALED BY AMERICAN TONGUES 390–409 The _Homo alalus_ or speechless man, a romance; linguistic stocks; the phonetic elements significant; examples; but not of same significance in different stocks; notion of _self_ and _other_; pronouns a late development; alternating consonants and permutable vowels; examples; phoneticism inadequate; difficulties thus created; counter-sense in language; notion of Being and Not-Being; incorporation; sentence-words; no dependent clauses; no tenses; no adjectives; no numerals; notion of Animate and Inanimate; classificatory particles; primitive man a _visuaire_. THE CONCEPTION OF LOVE IN SOME AMERICAN LANGUAGES 410–432 Significance of love-words; various origins. I. Algonkin love-words; various senses; highest forms. II. Nahuatl love-words; poverty of the tongue; made up by terminations; words for friendship. III. Maya love-words; singular derivations; the Huasteca dialect; the Cakchiquel dialect; comparisons. IV. Qquichua love-words; abundant; various meanings. V. Tupi-Guarani love-words; meaning of. Conclusions. THE LINEAL MEASURES OF THE SEMI-CIVILIZED NATIONS OF MEXICO AND CENTRAL AMERICA 433–451 Metrical standards a criterion of progress; those of the Mayas; of the Cakchiquels; of the Mexicans or Aztecs; of the Mound-Builders of Ohio. Conclusions.