( 483 ) 



strikiii.a-. There too we liiid n i>i-iiiinrv iiiin-c lollowcd 1m the "satellite," 

 and lliis ^()ll(»^^('d in ils liirn l»y llic tcrliarv |Misiii\(' iiiiaiic. The 

 lattei' is ('\-er Inilowcd hv a iie,L>a!i\(> afler-iiiiam'. In llic opiiiiur 

 (tf IIkss, llie |)i-iniai-\ intake and llic saU-llile are alsd followed |»v 

 neualixc aricr-iniaucs. A sclicnie of lli(> lolal of die scnsalion is 

 ,^■i^■<'ll hv him as a siniiso'i'd<' wilh a ra|iidlv decreasing' amplilndc 

 and an increasiim- pei'iod ; see ii,u-. 2, in which die dii'ccl iniut;'c 



FiK. 2. 



is repi'eseiited hv 1. the satellite hy o. the positive afler-iiiiage 

 hv 5, and hy (i die liiial. easily visihie ;d'lei'-iina,ue. Hkss |)releiids 

 to percei\-e likewise the Jieiiative afler-iniaii'es '2 and 4, which I have 

 ne\'er heen ahle to see: for se\eral reasons, not to he jii\'en here, I 

 seriously donht wlieHier llu^se af"ter-ima,u'cs 2 and 4 really exisl. 



Leavinu' this (piestion, i only wish to point out the close resenihlance, 

 (tHered hv the tactual sensation, following- a sinf;-lc fcehle toncli of 

 a pin-point, with the series of ])osiii\e aftei'-iinap,'cs of the eye, 

 repres(Mited hy the coinhinalion I, 'A and 5. The conrse of the 

 phenomena is tlu^ same in hoth ca^es : the iwhitlrc duration of 

 each snhdi\isi(»n is perfectly e((na] for hotli senses, only the ahsolnte 

 duration is somewhat lonu'er for the skin. 



Still another analouy is shown hy the (piality of the three separate 

 inia,i»'es heing ditferejd, as well for llie (w (> as for iIk^ skin. I wish 

 to lay great stress on the statement of this last fact, hecanse it 

 opens the [)Ossihility of a new conception. e(|nally dilferent from that 

 of (ioLDsciiFJUKK as from that of IIkss. Kncii the experiments of 

 (Tioi,i)S('iii'',ii)KH. alleged h\- him in faxoiii' of his hypothesis of snmmalio 

 arc suhject to another explanation. 



(ioF,i)S('iii',ii)KR ohsei-ved that one single induction-shock, liowc\cr 

 strong it iiia\- he, applied as a cutaneous stimnlns, is never ahle to 

 rouse the secondary sensation, whilst this was effected easily and 

 constanth h\ .'> or 4 sli(Md<s of I he induced ciiri-ent, even rather feeble 

 t»nes, following each other in rajtid succession. 



32 



Proceedings Royal Acad. Amsterdam. Vol. VI, 



