THE GENERAL SENSES. 273 



In extending the arm and moving it up and down, all three 

 of these sets of nerve endings are probably stimulated, and 

 impulses thence conveyed to the brain. 



Muscular Sense and General Sensibility. It is a 



matter of doubt whether or not the impulses from the 

 muscles are predominant, and consequently whether the 

 term " muscular sense " is the most appropriate. Peculiar 

 nerve endings have been found in the tendons, and the 

 joints are believed to have an especially rich nerve supply. 

 It is not necessary that we actively use the muscles to have 

 sensations of this kind. In passive moments, as the rais- 

 ing of the arm by another person, we have a "sense of 

 position" of the parts, a considerable share of which is 

 probably due to the tension of the skin and changes in the 

 joints. There is, of course, some tension of the muscle, 

 even in this passive movement, that might affect nerve 

 endings in it. The muscular sense is closely related to the 

 general sensibility already mentioned, if not a modified 

 form of it. 



Importance of Muscular Sense. It is difficult to real- 

 ize the importance of this sense in our daily experience. 

 We probably underestimate it, and attribute to sight too 

 much of our knowledge of the external world. The funda- 

 mental facts concerning the objects about us are not ob- 

 tained through sight alone. Such knowledge is based on 

 complex judgments concerning the meaning of auditory 

 and visual phenomena, according as they have, in past ex- 

 perience, been interpreted by tactile and muscular percep- 

 tions. That is, when reduced to its simplest terms our 

 most practical and important knowledge of the world is 

 the outgrowth of tactile and muscular perceptions ; by and 



