A complete record of the teachings of the established sciences with regard to the voice demands the separate consideration of the four sciences mentioned. Each will therefore be treated in turn. In the case of each of these sciences it is seen that the most essential facts of the vocal action have been definitely established. Many questions still remain to be satisfactorily answered which are of great interest to the theoretical student of the voice. Yet in spite of the lack of exact knowledge on these points, enough is now known to furnish the basis for a practical science of Voice Culture. _The Anatomy of the Vocal Mechanism_ This subject has been so exhaustively studied that nothing new can well be discovered regarding the muscular structure of the vocal organs. In all probability the reader is sufficiently acquainted with the anatomy of the larynx and its connections. Only a very brief outline of the subject is therefore demanded. The muscles concerned with breathing call for no special notice in this connection. The special organ of voice is the larynx. This consists of four cartilages, with their connecting ligaments,--the thyroid, the cricoid, and the two arytenoids, and of nine so-called intrinsic muscles,--two crico-thyroid, right and left, two thyro-arytenoid, two posterior crico-arytenoid, two lateral crico-arytenoid, and one arytenoideus. The inner edges of the thyro-arytenoid muscles form the vocal cords. The hyoid bone, serving as a medium of attachment for the tongue, may also be considered a portion of the larynx. By means of the extrinsic muscles the larynx is connected with the bones of the chest, neck, and head. While the muscular structure of the vocal organs is thoroughly known, the actions of the laryngeal muscles in tone-production have never been absolutely determined. This much is definitely established: Vocal tone is produced when the vocal cords are brought together and held on tension, and the air in the lungs is expired with sufficient force to set the vocal cords in motion. The tension of the vocal cords can be increased by the contraction of their muscular tissues, the two thyro-arytenoid muscles; further, increased tension of the cords can also result from the tilting of the thyroid cartilage on the cricoid, by the contraction of the crico-thyroid muscles. It is also definitely proved that the pitch of the vocal tone varies with the state of tension of the vocal cords; increasing the degree of tension raises the pitch, decreasing the tension lowers it. As to the relative importance of the different groups of muscles in varying the tension of the vocal cords, nothing has been definitely proved.