The function of this muscle is to approximate the arytenoid cartilages. Its paralysis leaves the posterior borders of the cartilages separated, even though the vocal processes are by the action of the lateral crico-arytenoids made to approach the median line. There is left a triangular opening at the base of the cartilages, through which the air escapes in the act of speaking. This, the {85} cartilaginous portion of the glottis, remains patent even though the anterior three-fourths of the space be closed. The result is generally, but not always, a loss of speech. The air whistles through this opening, but phonation is difficult or absent. The causes are to be sought in the derangements resulting in the loss of power of the other muscles. Upon examination with the laryngoscope the triangular opening is readily seen. The ligamentous portion of the glottis is seen to close in the effort to speak, while the cartilaginous portion is widely open. There is no other morbid condition necessarily present. The trouble is frequently associated with paralysis of the adductors of the two sides--that is, the lateral crico-arytenoids. In these cases there is complete separation of the cords throughout the whole length. The DIAGNOSIS is easy except in instances where there is ankylosis of the articulation of the cartilages. Even in these cases a careful study of the parts, as revealed by the mirror, will enable the observer in most instances to recognize evidence of structural disease on the walls of the larynx. There will also be a history of some antecedent affection, such as syphilis or tuberculosis, or possibly arthritis. The course and termination of this form of paralysis depend largely upon the etiology in any given case. Paralysis of the Tensors of the Vocal Cords. It will be remembered that these are in two groups, the internal and external. The internal are the thyro-arytenoids. While their function is in part still a matter of discussion, it is very generally conceded that they have to do with the form and tension of the cords. Their paralysis produces a very marked derangement of the functions of the larynx as the organ of speech. They act ordinarily along with the crico-thyroids, but from the fact of their separate innervation it would seem very probable that they should be the seat of special functional derangements. In fact, it is true that their paralysis in a limited number of cases is found to be quite independent of any disturbances of the external tensors.