Other children of the same age do very much the same. The boy D, though he repeated cleverly what was said, was not good at naming objects when he was expected to do this of himself. He would say, e. g., _pilla_ for Spiegel (mirror). At this same period (twenty-five months) he could not yet give the softened or liquid sound of consonants (mouilliren). He said _n_ and _i_ and _a_ very plainly, and also _i-a_, but not _nja_, and not once "ja"; but, on the contrary, always turned away angrily when his father or I, or others, required it of him. But as late as the twenty-eighth month echolalia was present in the highest degree in this very vigorous and intelligent child, for he would at times repeat mechanically the last word of every sentence spoken in his hearing, and even a single word, e. g., when some one asked "Warum?" (why) he likewise said _warum_ without answering the question, and he continued to do it for days again and again in a vacant way, with and without the tone of interrogation (which he did not understand). From this we see again plainly that the imitation of sounds is independent of the understanding of them, but is dependent on the functions of articulation. These functions are discussed by themselves in the work of Prof. Fritz Schultze, of Dresden, "Die Sprache des Kindes" ("The Language of the Child," Leipsic, 1880, 44 pp.). The author defends in this the "principle of the least effort." He thinks the child begins with the sounds that are made with the least physiological effort, and proceeds gradually to the more difficult sounds, i. e., those which require more "labor of nerve and muscle." This "law" is nothing else than the "loi du moindre effort" which is to be traced back to Maupertuis, and which was long ago applied to the beginnings of articulation in children: e. g., by Buffon in 1749 ("Oeuvres completes," Paris, 1844, iv, pp. 68, 69), and, in spite of Littre, again quite recently by B. Perez[F] ("Les trois premieres Annees de l'Enfant," Paris, 1878, pp. 228-230, _seq._) But this supposed "law" is opposed by many facts which have been presented in this chapter and the preceding one. The impossibility of determining the degree of "physiological effort" required for each separate sound in the child, moreover, is well known. Besides, every sound may be produced with very unequal expenditure of force; but the facts referred to are enough for refutation of the theory. According to Schultze, e. g., the vowels ought, in the process of development of the child's speech, to appear in the following order, separated in time by long intervals: 1. Ae; 2. A; 3. U; 4. O; 5. E; 6. I; 7. Oe; 8. Ue. It is correct that _ae_ is one of the vowels that may be first plainly distinguished; but neither is it the first vowel audible--on the contrary, the first audible vowel is indistinct, and imperfectly articulated vowels are the first--nor can we admit that _ae_ is produced with less of effort than is _a_. The reverse is the case.