We have already seen that even the most imitative of vocalists, the talking birds, will invent wholly arbitrary sounds as denotative names,[214] and it would be psychologically absurd to suppose that they are superior to what primitive man must have been in the matter of finding expedients for semiotic utterance. Again, the clicks of Hottentots and Bushmen, whatever we suppose their origin to have been, certainly cannot have had that origin in onomatopœia; and no less certainly, as Professor Sayce remarks, they still survive to show how the utterances of speechless man could be made to embody and convey ideas.[215] Lastly, on the general principle that the development of the individual furnishes information touching the development of the race, it is highly significant that the _hitherto speechless_ child will spontaneously use arbitrary sounds (both articulate and otherwise) whereby to denotate habitual recepts. And even after it has begun to learn the use of actual words, arbitrary additions are frequently made to its vocabulary which defy any explanation at the hands of onomatopœia—not only, as in the cases above alluded to, where they are left to themselves, but even in cases where they are in the closest contact with language as spoken by their elders. I could quote many instances of this fact; but it will be enough to refer to one already given on page 144 (foot-note). When, however, these spontaneous efforts are not controlled by constant association with elders, but fostered by children of about the same age being left much together, the remarkable consequence previously alluded to arises—namely, a newly devised language which depends but in small part upon the principle of onomatopœia, and is therefore wholly unintelligible to all but its inventors.[216]