Having established the 'Americanism' and the originality of the negro folk-song, and having stated the presence of an African as well as European element, we may now attempt to point definitely to instances of both. Generally speaking, the African characteristics consist of rhythmic and melodic aberration, while the European ingredients find expression in the harmonic structure and the style of the melodies as far as they are influenced by that structure. But this statement is subject to qualifications. While the African, like every other exotic race, is generally innocent of harmonic science, travellers have brought evidences of a genuine natural feeling for harmony among the African tribes. Thus a German officer recounted to John W. D. Moodie[65] how his playing of an aria from Gluck's _Orfeo_ on the violin was immediately imitated _with accompaniments_ by the native Hottentots. Peter Kolbe, writing in 1719, testified to the Hottentots' playing of their _gom-goms_ in harmony, and Mr. Krehbiel records the singing of a Dahoman minstrel at the World's Columbian Exposition (1893) to the accompaniment of a Chinese harp as follows: 'With his right hand he played over and over again a descending passage of dotted crotchets and quavers in thirds; with his left hand he syncopated ingeniously on the highest tuned string.' According to the same writer, another investigator, Dr. Wangemann, transcribed a hymn by a Kaffir in which the solos were sung in unison but the refrain in full harmony. These instances should give some clue to the extraordinary ability of negroes to 'harmonize,' that is, improvise harmonies to a given melody.