54 GENERAL ANALYSIS. 



each kidney might, therefore, be most properly called 

 a half. 



117. THE ENTIRE MENTAL Group is double; and 

 each part is to be spoken of as Right and Left. There 

 are two Heads, the right and left, composed of two 

 brains, nearly separated by a deep fissure. The Cranium 

 is divisible into the right and left. The Ears, the Eyes, 

 the Noses, the Mouths are double so far as regards sen- 

 sation. The Muscles are right and left ; and although 

 those around the mouth are named as of the upper and 

 lower lips, or usually as the orbicularis oris (circular of 

 the mouth), as if a single muscle swept around the 

 mouth, they are divided by a thin tendon at the mid- 



FiG._72. Fig. 72 represents the muscles of 



the face, all of them evidently be- 

 ing double, except 13, which is also 

 double, the teudon at the middle 

 line of the upper and lower lips, 

 perfectly though thinly, separating 

 the right from the left. If a person's 

 right or left facial muscles are par- 

 I alyzed, he will be able to use only 

 pthe other muscles of the face includ- 

 that of both lips ffom the middle 

 line, and by a little practice any per- 

 one can exhibit the action of the 

 lips of one side in talking while the 

 other is quiet. Fig. 49 also shows 

 that each group of muscles has its 

 own nerves. 



die line. The Nerves also are double. The skin at its 

 surface is continuous, but when we pass down to its 

 nerves it is an organ of sensation, and composed of 

 the right and left, the line of division being most exactly 

 marked in some cases of paralysis, on one side of it sensa- 

 tion being perfect, and on the other altogether wanting. 

 The same is true of the Neck and Walls of the Trunk; 

 the Skeleton, Muscles, Nerves, Skin, and Blood-tubes of 

 those parts are exactly double. 



117. How ? Name parts in detail that are double. What is said of muscle 

 of lipa ? Describe Fig. 72. What other parts of members are double ? 



