THE RECEPTOR SYSTEM 209 



related with the fact that in voluntary movement we do not make 

 a conscious effort to contract any particular muscles: the higher 

 nerve-centers are merely concerned with the initiation of a given 

 movement of a given extent, and all the details are carried out by 

 lower co-ordinating centers. In ordinary daily life in fact we have 

 no interest whatever in a muscular contraction per se; all we are 

 concerned with is the result, and consciousness has never had need 

 to trouble itself, if it could, with associating a particular feeling or 

 a particular movement with any individual muscle. 



Muscular feelings are, as already pointed out, frequently and 

 closely combined not only with visual but also with tactile, in pro- 

 viding sensations on which to base judgments: in the dark, when 

 an object is of such size and form that it cannot be felt all over by 

 any one region of the skin, we deduce its shape and extent by com- 

 bining the tactile feelings it gives rise to, with the muscular feelings 

 accompanying the movements of the hands over it. Even when 

 the eyes are used the sensations attained through them mainly 

 serve as short-cuts which we have learned by experience to inter- 

 pret, as telling us what tactile .and muscular feelings the object 

 seen would give us if felt; and, in regard to distant points, although 

 we have learnt to apply arbitrarily selected standards of measure- 

 ment, it is probable that distance, in relation to perception, is 

 primarily a judgment as to how much muscular effort would be 

 needed to come into contact with the thing looked at. 



When we wish to estimate the weight of an object we always, 

 when possible, lift it, and so combine muscular with tactile, sensa- 

 tions. By this means we can form much better judgments. While 

 with touch alone just perceptibly different pressures have the 

 ratio 1 :3, with the muscular sense added differences of T V can be 

 perceived. 



Hunger. In discussing this sense we must first draw a distinc- 

 tion between true hunger and appetite. The latter is a feeling that 

 food would be acceptable, with usually a degree of pleasurable 

 anticipation included. It is often heightened by the odor and 

 taste of food. There is reason to doubt whether appetite should be 

 called a sense in the strict meaning of that term. It might, per- 

 haps, be better classed with fatigue, nausea, and the other feelings 

 mentioned in a former paragraph as not representing the results of 

 definite receptor stimulation. True hunger, on the other hand, is a 



