Edward Sapir (18841939). Language: An Introduction to the Study of Speech. 1921.
ragil man, the plural rigal; shibbak window, the plural shababik. Very similar phenomena are illustrated by the Hamitic languages of Northern Africa, e.g., Shilh14izbil hair, plural izbel; a-slem fish, plural i-slim-en; sn to know, sen to be knowing; rmi to become tired, rumni to be tired; ttss15 to fall asleep, ttoss to sleep. Strikingly similar to English and Greek alternations of the type singsang and leip-o I leave, leloip-a I have left, are such Somali16 cases as al I am, il I was; i-dah-a I say, i-di I said, deh say!
Vocalic change is of great significance also in a number of American Indian languages. In the Athabaskan group many verbs change the quality or quantity of the vowel of the radical element as it changes its tense or mode. The Navaho verb for I put (grain) into a receptacle is bi-hi-sh-ja, in which -ja is the radical element; the past tense, bi-hi-ja, has a long a-vowels, followed by the glottal stop;17 the future is bi-h-de-sh-ji with complete change of vowel. In other types of Navaho verbs the vocalic changes follow different lines, e.g., yah-a-ni-ye you carry (a pack) into (a stable); past, yah-i-ni-yin (with long i in -yin; -n is here used to indicate nasalization); future, yah-a-di-yehl (with long e). In another Indian language, Yokuts,18 vocalic modifications affect both noun and verb forms. Thus, buchong son forms the plural bochang-i (contrast the objective buchong-a); enash grandfather, the plural inash-a; the verb engtyim to sleep forms the continuative