[*] 176. The Present Stem is formed from the Root in all regular verbs in one of the following ways:— [*] a. In the First, Second, and Fourth conjugations, by adding a long vowel (ā-, ē-, ī-) to the root, whose vowel is sometimes changed: as, vocā-re (VOC), monē-re (MEN, cf. meminī ), sopī-re (SOP).1
[*] Note.--Verb-stems of these conjugations are almost all really formed from nounstems on the pattern of older formations (see § 174).[*] b. In the Third Conjugation, by adding a short vowel e/o 2 to the root. In Latin this e/o usually appears as i/u, but e is preserved in some forms. Thus, tegi-s (root TEG), ali-tis (AL), regu-nt (REG); but tegĕ-ris ( tegĕ-re ), alĕ-ris.
- The stem-vowel e/o ( i/u ) may be preceded by n, t, or sc:3 as, tem-ni-tis, tem-nu-nt,tem-nĕ-ris (TEM); plec-ti-s(PLEC); crē-sci-tis (CRĒ).
- Verbs in -iō of the Third Conjugation (as, capiō, capĕre) show in some forms an i before the final vowel of the stem: as, cap-i-unt (CAP), fug-i-unt (FUG).
- By the repetition of a part of it (reduplication): as, gi-gn-e-re (GEN).
- By the insertion of a nasal (m or n): as, find-e-re (FID), tang-e-re (TAG).
[*] Note 2.--In some verbs the final consonant of the root is doubled before the stemvowel: as, pell-i-tis (PEL), mitt-i-tis (MIT).[*] e. Some verbs have roots ending in a vowel. In these the present stem is generally identical with the root: as, da-mus (DA), flē-mus (stem flē-, root form unknown).5 But others, as rui-mus (RU), are formed with an additional vowel according to the analogy of the verbs described in d.