3l6 THE EVOLUTION OF MAN. 



the vertical curtain which Ave call the soft palate, and in 

 the centre of the lower part of Avhich is situated the 

 uvula. A glance with the mouth open into a mirror is 

 sufficient to show the form. The uvula is of importance, 

 because it occurs only in Men and in Apes. On both sides 

 of the soft palate are the tonsils (tonsillce). Through the 

 gate-like arched opening situated beneath the soft palate, 

 we pass into the throat-cavity (pharynx; Plate V. Fig. 

 16, sh), which lies behind the mouth-cavity. This is only 

 partly visible in the open mouth when reflected in the 

 mirror. Into the throat-cavity a narrow passage opens on 

 each side (the Eustachian tube of the ear), which leads 

 directly into the tympanic cavity of the ear (Fig. 244, e, 

 p. 260). The throat-cavity is continued into a long 

 narrow tube, the gullet {oesophagus, sr). Through this 

 the masticated and sw r allowed food passes down into the 

 stomach. The wind-pipe (trachea, Ir) also opens into the 

 upper part of the throat, and leads thence to the lungs. 

 The opening of this is protected by the epiglottis, over 

 which the food passes. The respiratory organs, the two 

 lungs (Plate IV. Fig. 8, hi), are situated, in Man, as in all 

 Mammals, in the right and left sides of the breast-cavity 

 (thorax), and midway between them is the heart (Fig. 

 8, hr, hi). At the upper end of the wind-pipe (trachea), 

 below the epiglottis just spoken of, is a peculiarly differ- 

 entiated section, the larynx, which is protected by a carti- 

 laginous frame. The larynx is the most important organ 

 of the human voice and speech, and also develops from a 

 part of the intestinal canal. In front of the larynx lies the 

 thyroid gland (thyreoidea), which occasionally enlarges to 

 the so-called " goitre." 



