ON LATERAL PBESSUllE. 169 



In the act of sucking, in mastication, and in de- 

 glutition, tlie tongue and the palate are as much 

 dependent upon each other for the proper per- 

 formance of their functions as are the two rows of 

 teeth upon each other in eating; and therefore, when 

 the tongue is pressed against the palate, either to 

 produce the vacuum for sucking, or to compress 

 portions of food, the very act of pressing it 

 forcibly upwards tends to its expansion, and the 

 corresponding expansion of the jaws previously 

 alluded to as a favourable prognosis of the ulti- 

 mate regularity of the teeth. 



In every variety of form of the dental arch, a 

 particular shape of the palate will invariably exist 

 in connection with some few other peculiarities 

 which are corresponding accompaniments. Thus, 

 where the palate is broad and shallow, the palate 

 processes of the upper maxillse presenting a con- 

 siderable area of horizontal surface, and gradually 

 shelving off to the alveolus at an angle of about 45°, 

 the tongue large and broad, the teeth are com- 

 paratively small and wanting in boldness of outline, 

 and rarely or never irregular in position, although 

 occasionally producing supernumerary or " pin" 

 teeth among the upper incisors. But in the 

 opposite extreme, we shall find the palatal vault 

 deep, narrow, and angular; the tongue thick, 

 narrow, and tapering ; the alveolar ridge thick, 

 prominent, and almost perpendicular; the teeth 

 large, and fully developed, thickly but unevenly 



