THE DECLENSION OF NOUNS 231 tf-stems, though it must have extended to them at a very early period. The reason for this is that the action nouns of these classes would be* expected, according to the general analogy, to have been originally neuters, and this is borne out by the exist- ence of survivals of the type ; on the other hand in the case of the agent-noun/adjective types there is evidence of a vrddhied treatment parallel to that of the r- y n- and 5 -stems, and though this is rare in the historical period, it can be shown to have been much commoner earlier. The probability is that the nominative s was originally proper to the adjectival thematic stems, since they are definitely a class apart. Its extension to the i- and u- stems is not difficult to understand, since like the thematic stems they are vocalic stems. In this process the morphological distinction and agent-noun /adjective appears to have counted very little, and the 5 of the nominative (and with it the distinc- tion between norm and acc.) became early attached even to the action nouns of these classes. In this way the majority of such nouns acquired the masc, or fern, (earlier, common) gender. Historically they do not take s in the nom. sg. because they have gender, but rather they have acquired gender as a result of taking -s. In the same way sterns in occlusives were from an early period characterised by s in the nom. sg., and this regard- less of whether they were action or agent nouns. In mono- syllabic stems the s was also added after consonants other than occlusives (nasals, Gk. Krais ; H, Skt. dhis, bhUs). The feminines in -d and those in -1 of the devi class have no special sign for the nom. sg. To this extent they agree with the neuters. The action nouns ending in these suffixes originally were neuters, and in the case of this suffix the adjectival type, which was specialised as a fern, formation was always less clearly distinguished from the action noun type than was the case with other suffixes. Accusative Singular, Masc. and Fern. The accusative singular masc. and fem. shows no such variation. The termination appears as -m after vocalic stems ( dsvam , Lat. equum ; agnim , Lat. ignem, etc.) and - am after consonantal stems ( padarn , rdjanam, pitdram , etc.). In the latter case Greek has a out of m ( 77 -oSa, irarapa) and, this is the form which would be expected phonetically, but Indo-Iranian substitutes the fuller form which has the advantage of greater clarity. In some languages (Gk., Celt., Germ.) this final -m changes to -n, as it also does in
