SENSATIONS TOUCH 193 



are distinctly local in their character. Such sensations are called 

 special sensations. Others are not localised, but are produced 

 through the agency of nerves which are very widely distributed. 

 These sensations are called common or general sensations, and 

 by them we are made aware of the general condition of the body. 



Among the common sensations may be mentioned pain, 

 warmth, hunger, fatigue, and faintness. Although some of these 

 sensations are sometimes distinctly localised, yet, at the same time, 

 they are accompanied by a general sensation. For instance, during 

 hunger a distinct pain is felt in the region of the stomach, while 

 there is also a feeling of general discomfort. 



One of the common sensations is that which has been 

 termed the 'muscular sense.' It is that sensation by which we 

 become acquainted with the condition of the muscles. Although 

 the mind may be unconscious of the existence of the muscles of any 

 particular part, yet it is made aware of their condition, and is able to 

 regulate their contraction with extreme precision. Thus, when 

 walking on a windy day, we incline our bodies in proportion to 

 the force of the wind. A person, by means of this sense, may 

 perform such complicated acts as writing or pianoforte-playing 

 without the aid of sight. It is the muscular sense which enables 

 us to estimate the weight of a body by the effort required to lift it. 

 We are most conscious of this muscular sensation when we make 

 the muscles rigid by an effort of the will. 



The special sensations are five in number. They are touch, 

 smell, taste, sight, and hearing. 



Sensations are also classified as objective and subjective. 



Those sensations which are produced by external objects or 

 conditions are called objective sensations. Sometimes, however, 

 the exciting cause is a peculiar condition of the cerebrum itself, 

 and the sensations thus produced are termed subjective. As 

 examples of these may be mentioned noises in the ears, flashes of 

 light before the eyes, and peculiar odours experienced when there 

 is no external cause to produce them. The mind generally refers 

 such sensations to external objects, and hence arise illusions. 



Sensation may be produced by the irritation of a sensory nerve 

 without the agency of the corresponding organ of sense. Thus, 

 the sensation of sound may be produced by the irritation of the 

 auditory nerve. The irritation of a nerve of special sense however, 

 does not produce pain. 



The sense of touch is sometimes classed among the general 

 sensations, inasmuch as it is very widely distributed, and is so 

 closely allied to feeling and pain, which are general sensations. 

 But touch proper is a sensation by which we gain a knowledge of 

 the external world, while feeling and pain are sensations by which 



