In his description of the disease which bears his name, Gilles de la Tourette used the expression echolalia to denote a certain phenomenon of occasional occurrence among those who tic. The patient (says Guinon) repeats echo-like the sounds he hears around him, and like the echo his reproduction of them is more or less lengthy. In its mildest form the symptom may consist in the repetition of a simple involuntary "ah!" which some one near by has ejaculated, or the last word or two of some one's talk is mimicked, or in a more advanced stage the whole of a phrase is reproduced. As a general rule the "echo" is rather obtrusive, but its commencement at least may be very different, the patient being astonished to find himself repeating in a subdued tone of voice what he hears others saying; and, struggling in fear to rid himself of the habit, he ends by sinking into a state of actual anguish. It is at this moment that he fails to inhibit his impulses and gives vent to the word he has been endeavouring to check, which he may repeat loudly and violently in a sort of fury. The fidelity and clearness with which the utterances of others are imitated are remarkable. Sometimes by an effort of the will the patient is able to suppress, it may be imperfectly, the impulse to echo, so that while his tongue is under his control, his will gives rein to his other tics, and a regular muscular debauch takes place. In the mildest cases he can replace a word by a movement, by a little cough or an insignificant "ahem!" but not beyond a certain point, for he will thus restrain himself only when he is forewarned; a sudden and unexpected ejaculation in his neighbourhood will catch him off his guard. In spite of their frequency among those who are addicted to tic, echolalia and echokinesis cannot be enumerated with the tics, seeing that their exhibition is dependent on the actions of others, whereas once a tic is established it requires no stimulus from without for its manifestation. Of course their affinity to the tics is very close: they spring from the same soil; they represent in the adult the persistence and amplification of the child's propensity for imitation, and therefore in their own way postulate a degree of mental infantilism. Echolalia in the blind has been made the subject of an interesting study by Noir. The echolalic repeats abruptly and rapidly what is said by others in his presence. That he does not stop to reflect is attested by his mimicry of bizarre words, technical terms, even of idioms in a foreign language.