THE VERB 293 in dealing with the formation of nouns is evident, and it is in accordance with the fact that nominal and verbal stems are formed fundamentally on the same principles. The enlargements of the verbal roots are simply incorporated suffixes, and do not require, as is sometimes considered, a separate morphological classification. All the IE consonants and semivowels can appear in this function, just as they can in the formation of nouns. In the latter case those so used with any frequency are, as has been seen, necessarily limited in number. In the case of the enlargements the distribution is more even, and with the ex- ception of s and H, which had a considerable part to play in the IE conjugation, the common nominal suffixes do not appear correspondingly frequently as enlargements. The suffixes n and r, for instance, which are of very great importance in nominal stem formation, appear only rarely as enlargements. This would suggest that, on the whole, the enlargements of the verbal root reflect a comparatively early stage of IE stem- formation, that is to say a period when the emphasis on a com- paratively few suffixes out of the large number available had not developed to the extent with which we are familiar later. It is also clear that the growing clarity of the distinction between verb and noun, which evolved in the later pre-history of Indo- European, tended to prevent the incorporation of such suffixes (e.g. r and n) which were felt as predominantly nominal. In their guna grade such roots may appear in two forms, on the one hand that which appears in cet- * perceive sec- ‘ pour rod- ‘ weep etc., and on the other hand that which is seen in tras - ' fear ksad- ' divide sro- ‘ hear ', etc. That is to say, either the root or the enlargement may have the guna, but, in accordance with the principles of IE apophony, it is not pos- sible that both should have it. The difference between the two types of guna form is without any significance as far as the meaning of the roots is concerned, or their conjugation. It is only in connection with nominal stems that this kind of dis- tinction is significant. There it provides the distinction between neuter action nouns and adjectives or agent-nouns. Since these roots were originally stems, and in the early period, when noun and verb were less clearly distinguished, as much nominal as verbal, it is reasonable to assume that the distinction in form between the two types of extended root, was originally the same as that which is fundamental in the formation of nouns.
