We divide each expression in the given language into the smallest sequences of phonemes which have what we consider the same meaning when they occur in other expressions, or which are left over when all other parts of the expression have been divided off […]. The resultant minimum parts we call not morphemes, but MORPHEME ALTERNANTS. It is useful to generalize this definition of morpheme alternant by taking sequence to mean not only additive sequence (the addition of phonemes), but also zero (the addition of no phonemes), negative sequence (the dropping of a phoneme), and phonemic component sequence (the addition of a physiological feature of phonemes). In Hidatsa, we have a minus morpheme, consisting of dropping the final vowel mora, with the meaning of command: 'cixic' ‘jumped’, 'cix' ‘jump!’, 'ikaּc' ‘he looked’, 'ika' ‘look!’. In 'took' we have two morphemes: 'take', and /ej/ ~ /u/ ‘past time’. The latter occurs also in 'shook' as compared with 'shake'. It is a combination of negative and additive sequences: dropping /ej/ and adding /u/. Another negative-additive morpheme is a /a/ ~ /e/ ‘plural’, which occurs in 'men' as compared with 'man'.
- Harris (1942a), a pag.170