280 PHYSIOLOGY OF MUSCLES AND NERVES. 



projects every sensation wliich reaches the conscious- 

 ness outward, that is, to where the cause of the excite- 

 ment is normally. This so-called laiu of eccentric 

 sensations finds an easy explanation in the supposi- 

 tion that the conception of the locality of the efficient 

 cause is gained from experience.^ It will easily be 

 understood that this necessarily follows from the cha- 

 racters which we have ascribed to the nerve-cells. 

 When the nerve-cell is irritated, the same sensation 

 and the same conception must always result. Just as it 

 makes no difference in the case of a muscle whether the 

 excitement conveyed to it by a motor nerve starts from 

 a higher or from a lower point on the nerve, or whether 

 the nerve has been irritated mechanically, electrically, 

 or by the will, so the process in the nerve-cell does not 

 depend on the locality or the nature of the excite- 

 ment. AYhen the circumstances which give rise to 

 the irritation are abnormal, the result is an illusion 

 of the senses, that is, a false cause is assigned to a 

 perfectly clear and true sensation. 



8. The nature of the last of the capabilities which 

 we have attributed to the nerve-cells, the retardation 

 of a motion, is still very obscure. The fact of retarda- 

 tion is as yet principally known in the case of auto- 

 matic motion, though retardation of reflex action also 

 occurs, as may be inferred even from the fact that the 

 rise of reflex actions is hindered by the activity of the 

 nerves, especially when this originates from the brain. 

 The respiratory movements being of all automatic move- 



' Details of this matter, into which we cannot enter further 

 here, will be found in Bernstein's The Fice Senses of Man (Inter- 

 national Scientific Series, vol. xxi.), and in Huxley's Elementally 

 Physiologrj. 



