account for the modificatory elements, such as _dh_, _g_, _k_, _p_, _d_, _s_, _n_, _t_, _r_, as remnants of other roots, whether predicative or demonstrative. Thus Curtius compares +tar+ or +tra+, with +tras+, +tram+, +trak+, +trap+; +tri+ and +tru+ with +trup+, +trib+, taking the final consonants as modificatory letters. But what are these modificatory letters? Every attempt to account for them has failed. If it could be proved that these modificatory elements, which Curtius calls _Determinatives_, produced always the _same_ modification of meaning, they might then be classed with the verbal suffixes which change simple verbs into causative, desiderative, or intensive verbs. But this is not the case. On the other hand, it would be perfectly intelligible that such roots as +mark+, +marg+, +mard+, +mardh+, expressing different kinds of crushing, became fixed side by side, that by a process of elimination, their distinguishing features were gradually removed, and the root +mar+ left as the simplest form, expressive of the most general meaning. Without entering here on that process of mutual friction by which I believe that the development of roots can best be explained, we may say at least so much, that whatever process will account for the root +yu+, will likewise account for the root +yuj+, nay, that roots like +mark+ or +mard+ are more graphic, expressive, and more easily intelligible than the root mar. However, if this view of the origin of roots has to be adopted, it need not altogether exclude the other view. In the process of simplification, certain final letters may have become typical, may have seemed invested with a certain function or determinative power, and may therefore have been added independently to other roots, by that powerful imitative tendency which asserts itself again and again through the whole working of language. But however that may be, the sharp line of distinction which Curtius draws between the First Period, represented by simple, and the Second Period represented by derivative roots, seems certainly no longer tenable, least of all as dividing _chronologically_ two distinct periods in the growth of language.