Stuttering and stammering should not be confounded, as they are distinct forms of speech disturbance. In stuttering, there is no lack of ability to pronounce sounds distinctly, but a want of power to combine sounds together in forming syllables and words. Single sounds can be articulated without difficulty, but when the patient attempts to speak, an impediment occurs. The impediment consists in spasmodic contraction of some of the muscles involved in the production of sounds. The impediment may show itself as soon as the patient begins to speak, or not until several words have been uttered. It is most likely to occur when the word which the individual attempts to pronounce begins with a consonant, especially with an explosive sound. In very severe cases, the sufferer, in his attempts to utter an explosive sound, sometimes works himself into a state of great agitation, his heart palpitates, his face becomes red with conges tion, profuse perspiration breaks out, and he presents an almost maniacal appearance. The paroxysm often continues until it becomes necessary for the patient to take breath. When the attempt is renewed, or it may be just as the patient is almost exhausted, the refractory organs perform their function, and the required sound is produced. In mild forms of the affection, there simply the repetition of particular letters or syllables.

This affection presents many peculiarities, among which is the fact that stutterers can often sing or whisper without difficulty. Many persons affected in this way have no trouble in speaking when alone, in the dark, or when with persons with whom they are intimately acquainted.

Anything which increases nervous excitability, greatly exaggerates the difficulty. In one case, the patient was entirely unable to speak a word when exhausted by a night's watching. Very frequently the stutterer will speak with perfect distinctness when asked to stutter. Stuttering is generally more marked in the morning than in the evening. In some countries the affection is quite common. Statistics show that in France there is one stutterer for every thousand persons, and in ten years nearly seven thousand persons were exempted from military service on account of stuttering. It is still more frequent in Germany. It is said that stuttering is wholly unknown in China, a fact which is undoubtedly due to the rythmical character of the language. A curious fact is mentioned by Colombat, who states that a Frenchman who learned Chinese was able to speak the acquired language with fluency, although he stuttered badly in his native tongue.

A tendency to stutter seems to be hereditary in families. The habit is often acquired by association with stutterers. It occurs about ten times as frequently in males as in females, and is most common in persons of nervous and excitable disposition.

Temporary stuttering is sometimes produced by dissipation, smoking, indigestion, loss of sleep, and other causes which produce great nervous exhaustion. Stuttering and stammering may be combined in the same individual, although the two diseases are distinct.