[…] the classes of 15.4 [Alternative Procedure: Classes of Morpheme-in-Environment], and any morpheme classification used for chapter 16 [Morpheme Sequences], are classes of morphemes-in environments, so that a single morpheme or morphemic sequence (or in any case a single phonemic sequence) may in one environment be a member of one class and in another environment a member of another class. This is only partial overlapping of morpheme classes, and given two different utterances containing the same morpheme we can tell to which class the morpheme belongs in each utterance by noting the different environments. In the case of 'I can tell my horse’s' (or: 'horse is) running' […], there is a segment /Əz/, member of a morpheme {’s}, member of class 'Na', and a segment /Əz/, member of a morpheme {be}, member of class 'V'.
- Harris (1951), a pag.271, n.24

Partial overlapping may also occur among the parts of segments […]. Thus [h] in 'hill' is a member of phoneme /h/; but the somewhat similar [h] of 'pill' was included in the segment [pʰ] […]. A different case arises with the crux of chapter 4 [Phonemic distinction], fn. 11, in which two distinct sounds were freely varying repetitions of one another in some utterances, but constituted different not mutually substitutable segments in the other utterances: [bgƏr’] and [bqƏr’] ‘cow’, but only [gr’a‘] ‘squash’ and [qr’a‘] ‘ringworm’; similarly, only [γrƏg] ‘he was parched’ and [γrƏq] ‘it sank’. If we can show a difference in phonemic environment (short of listing all the utterances) between the cases where the two vary freely and those where they do not, we will say that there is partial overlapping: in the first environment [g] is a free variant of the /q/ phoneme, and in the second it is a member of the /g/ phoneme. The /q/ phoneme then will have free members [g] and [q] in the first environment, and only [q] in the second (while /g/ will have only [g] in the second, and will not occur in the first).
- Harris (1951), a pag.65, n.14