3. _In phonation and articulation._—The soft palate is here of considerable importance, inasmuch as it is needed to cut off the naso-pharynx and nasal cavities from the oral pharynx. When defective or paralysed, a certain amount of nasal resonance is imparted to the voice, which, however, is less noticeable during vocalisation than in articulation. For the production of clear normal voice-sounds it is essential that the separation between nose and mouth should be absolute, except for the sounds _m_, _n_, and _ng_. The American twang is probably due to a slight relaxation of the soft palate, permitting a small percentage of voice-sounds to pass through the nose. Dr. N. W. Kingsley[41] has recently published some excellent diagrams illustrating the position of these parts during the production of definite sounds, and for all, except those mentioned above, the velum is horizontal, and in contact with the posterior pharyngeal wall. CHAPTER III. DEVELOPMENT.[42] _Normal development of mouth, face, nose, and teeth—Ossification—Development of intermaxilla; old ideas (Goethe’s, &c.); Albrecht’s theory—Harelip; position of cleft in alveolus, and in lip—Dentition; accessory teeth—Development of other deformities._ Before discussing from an embryological standpoint the various deformities which we have already described, it is essential for us to consider the normal process of development of the parts entering into their formation. About the end of the third week of intra-uterine life, the anterior cerebral vesicle becomes acutely bent over the end of the notochord, and a marked depression is seen on the ventral aspect of this, constituting what is known as the _Stomodæum_, or primary buccal cavity. This, however, is formed rather by the outgrowth of surrounding processes entering into the formation of the facial elements than by any definite or distinct involution of epiblast. The cavity is bounded posteriorly and superiorly by the cephalic flexure of the cerebral vesicles, and inferiorly is separated from the cephalic portion of the intestine by a septum. This becomes perforated at a slightly later date (eighth or ninth week), and communication is thus established between the stomodæum and intestine. Anteriorly, the opening is at first stellate in shape (Fig. 29), but soon assumes the form of a transverse cleft by the union in the middle line of the first pair of post-oral branchial arches, in which are developed the primary cartilaginous bars on either side, known as Meckel’s cartilage, the anterior part of which goes to form the inferior maxilla, and the posterior part the malleus. The soft parts around develop into the lower portion of the cheek, the lower lip and chin (Fig. 30).