CHAPTER X, 



THE SENSES. 



WE have already learned that one of the chief functions of the nervous 

 system is to correlate the parts of the organism into a unity, and the 

 organism as a whole with its varied and changeful environment. The 

 animal is no independent entity, but rather part and parcel of its environ- 

 ment to an extent not often realized. Just as the whole animal has an 

 environment scarcely ever twice alike, so also has each of the organism's 

 parts, large or small. It is the main function then of the sense-organs, 

 so called, to help this double adaptation. The sense-organs are the 

 peripherally terminal portions of the afferent nervous system, the means 

 by which the latter connects itself with its local environment. Homol- 

 ogous to the sense-organs at the periphery of the afferent nerves are the 

 muscles and the glands at ,the periphery of the efferent set of nerves. 

 The former receive for transmission the /messages from the "environ- 

 ment" as already defined; the latter perform in the environment, within or 

 without the organism, the bidding of the animal's will whether "reflexly" 

 or "voluntarily" performed. All of these from one point of view are but 

 parts of the nervous system; functionally, however, every bodily part is 

 sovereign and none the servant of any other. Just as in this chapter we 

 consider the receptive organs in the periphery of the afferent nervous 

 system, so in the next chapter the muscles are discussed the two homol- 

 ogous agents of the individual as expressed through his neural fabric. 



These are the afferent nerve-endings or, less correctly, the sense-organs. 

 The term "sense-organ" is an old and accepted one. From the modern 

 view-point as to the relations of body and mind it is somewhat misleading, 

 however, since it implies that whenever a sense-organ acts it represents 

 a conscious sensation. It is likely, indeed, that this is so, that each one 

 of the millions of afferent fibrils in the nervous system, centripetally 

 transmitting some impulse, contributes to the mass of consciousness. 

 This is the basis of the notion of consciousness to be found stated below 

 (see page 405). If, however, we always think of the impulses passing 

 inward through the sense-organ gates as afferent rather than as "sensory" 

 we shall be making no hypotheses and be sure we are thinking rightly. 

 This is the more important because it is becoming more and more appar- 

 ent that it is the organism which is conscious, rather than the mere 

 nerve-cells, and that at any rate to prove that the efferent impulses are 

 not accompanied by "sensation" is quite impossible. Whichever theory 

 of the mental process is taken as the basis, in the majority of the actions 

 of sense-organs (including of course the cutaneous and tendo-muscular 



