136 THE AMERICAN MONTHLY [May, 



in the direct line of the tube there are others which are 

 separate from it anatomically but directly connected with 

 it by ducts or passages which bring the secretions of 

 these connected organs into the tube itself. The sali- 

 vary glands are organs of this sort as well as the liver 

 and the pancreas. In the case of all of these organs two 

 functions are notable namely motion and secretion, in the 

 tongue in addition there is the function of sensation, 

 both of taste and touch, in a high degree. The study of 

 the structure of the organs has to be guided by the facts 

 of their use and the two aspects of their study are thus 

 complementary the one of the other. 



The tongue as a whole in the mammals is larger 

 behind where it is attached to the floor of the mouth 

 chamber and to the throat, and elongate in front. It is 

 composed of muscular tissue which material is covered 

 with epidermis, the character of which latter is peculiar 

 on the upper surface, being thrown into certain " pap- 

 illae" or elevations of various shape in different parts. 

 The muscular part of the tongue can be compared with 

 the outer coat of the alimentary tube and the epidermis 

 with the mucous coat, the two layers are not however 

 loosely related as they are in the rest of the tube but 

 are in the closest relation, the arteries lie in the level 

 between the outer and the muscular layers which thus 

 corresponds with the submucous coat. The extreme mo- 

 bility of the tongue is not matched by the power of any 

 other muscular organ in the body, and the range of mo- 

 tion is also enormous, this is attained through the pres- 

 ence in the bulk of the structure of sets of striped mus- 

 cular tissue each one of which is composed of fibres run- 

 ning parallel. These fibres run in many difl'erent direc- 

 tions, some crossing from left to right, others running 

 lengthwise and still others running vertically to the sur- 

 face. The contractions of one or other of these sets 

 would give rise to resultant motions of the organ. I;^ 



