We see that, although the development of quantity may look like a back and forth movement (lengthening >< shortening), these outwardly identical developments have different functions if the prosodic form of the root morpheme is taken into consideration.
The Middle Germanic quantity shift has led to a prosodic emphasis on the root morpheme and to a shift of the post-vocalic consonant into coda position while simultaneously retaining the extrametrical element during the consonant lengthening. In the ensuing consonant shortening in the contact correlation only the onset segment is affected, which disappears and thereby ensures a complete coincidence of the boundaries of syllable and morpheme in words with close contact. The vowel shortening in contact correlation leads to the same result. Consonant and vowel lengthening in apocope, which was carried out after the contact correlation had been established, results in the root becoming trimoraic. In these varieties, quantity, in combination with the stød, is to be interpreted as part of the morphosyllabic tone.
Yet, despite the different functions of the above-mentioned changes in quantity, there is one thing that they all have in common: They can be interpreted as successive steps in the prosodic development of the Germanic root morpheme, bearing witness to the development of the Germanic languages in the direction of morphosyllabism, thereby increasing the similarity of the Germanic languages to the morphosyllabic languages of South-Eastern Asia (cf. Kuz’menko 1991).