280 niYSiOLOiiV m Mtsn.Ks AND M:I;\ i .-. 



projects every sensit ion which readies the conscious- 

 ness "lit ward, that is, to where the cause of the excite- 

 ment is normal! v. This so-called Id in of ec<'< -ulr'n- 

 Sensations finds an easy explanation in the supposi- 

 (inn that the conception of the locality of the efficient 

 cause i> gained from experience. 1 It will easily be 

 understood that this necessarily follows from the cha- 

 racters which we have ascribed to the nerve-cells. 

 \Vlien the nerve-cell is irritated, the same sensation 

 and the same conception must always result. Just a> 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 docs not 

 depend on the locality or the natiire of the excite- 

 ment. When the circumstances \\hich MJ\C 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, t he retardation 

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

 tion is as yet principally known in the ca<e of auto- 

 matic motion, though retardation of reflex action ;dso 



ocnirs. as may be inferred even from the fact thai the 

 rise of reflex actions is hindered by the activity of the 

 nerves, especially when this originates from the brain. 

 The n-spiratorv movements being of all automatic mo\e- 



1 l>.-t;iils ( .r tlii> iintirr, into which \\ c c immt ruler furtlnr 

 v.iil !., fnund in InTiist. -iii's '/'//c I-'irf Si'iisi-ii iff Mnn (Intcr- 

 n.-il i"ii:il Srii'iil ilic Srrii-s, vul. xxi.). :>IH] in Huxli-y's l'.l< nn'n tanj 

 Physiology, 



