One of the alternate shapes is the ‘base form’, and the other or others are said to replace the base form under specific conditions where, otherwise, there would be an arrangement of phonemes contrary to the phonemic pattern of the language. (279-280)
- Hockett (1958), a pag.279

The base form in automatic alternation is the alternant which appears in those environments in which the phonemic habits of the language do not force the choice.
- Hockett (1958), a pag.282

The recognition of one representation of a morpheme (or of a larger form, say a word) as base form is sometimes merely a matter of descriptive convenience, but sometimes it has deeper significance.
- Hockett (1958), a pag.281