Umlaut of a > ä : Original IN lima > Dayak limä, "five".
Umlaut of a > e : Original IN hatay > Sumbanese eti, "heart".
Umlaut of a > ö : Original IN patay > Bontok padöy, "to kill".
Umlaut of o > e : Toba subdialect oyo > Toba eo, "urine".
Umlaut of u > ü : Original IN babuy > Bontok fafüy, "pig".
Note. — The symbol ä is used by Hardeland for an a modified by Umlaut in Dayak, and I have retained it.
253. Gayo has a sound similar to the German ö, but not originating through the modifying influence of an i, as in dödö, "breast" < Original IN dada.
254. Umlaut may be a preliminary step towards more complete assimilation. Original IN lima appears in Dayak as limä; and Hova, which is very closely related to Dayak, has dimi.
255. Dissimilation is rarer in IN than assimilation.
256. Dissimilation occurs:
I. If two similar sounds would otherwise follow one another. The duplication of Modern Javanese ro, "two", takes the form of loro. Original IN babuy, "pig", and babah, "to carry", appear in Mandarese as bagi and baga respectively.
II. If three similar sounds would otherwise follow one another. Original IN aṅin, "wind", appears in Bugis as aṅiṅ, but maṅinaṅ, "to dry in the air", has preserved the n through the operation of dissimilation. As in waṅuṅĕṅ, "to raise", from waṅuṅ, "to stand up" < Original IN baṅun, the same principle has not been at work, we may assume that in maṅinaṅ the vowel i has been a contributing factor. — Or is this case simply an application of the rule in § 210, I ?
257. Dissimilation operates either with or without contact :
I. Dissimilation with contact: e.g. in Toba in the case of s + s, when these two sounds would otherwise come together, e.g. in lat-soada, "not yet" < las, "yet" + soada, "not".
