MOVKMKNTS, KTC., ol' KliKSII-WATEIf. l'I-AX.\ l.'l A NS. 001 



(>l>.sei'VC(l at Llio uiiodu uud is, tis shown ])y tlic loiiii taken \>y 

 the part reacting-, a contraction oftlio Ion (^-i t luli nal niiisclc- 

 fi])rcs_, wliilc I lie (il)rc's of tlic circiihir ;ui<l transverse Kystem 

 are relaxed. Jn other words, the ciii-i'ent only alTects those 

 fibres which hear a, definite orientation with r(rl:i,li(jn to direc- 

 ti(jn oi' its jhnv, vi/. those which ai-e ])ar!iHcl with it. Now it 

 has been shown in an eai-lier ])ai-t oi' this ])a|)(M' that in the 

 ordinary ne^^ative reaction the tnrnin<^- awjiy i'rointhe stimulus 

 is produced l>y a contraction oi' the cii-culai-, transverse, and 

 dorso-ventral fibres (})rincipa]ly the cii'cular) on the side 

 stimulated. I'^videntiy when the ;iiiiiii;il is at right angles to 

 the direction of the flow of the current the only muscle-fibres 

 in tiie body \vli(;se longitudimil axes are in line with the 

 current are the fibres of the circular and transverse systems. 

 Unless it is assumed that the current acts differently in one 

 case from in iinothei' theic is no ajtparent i-eiison why, when 

 the animal is in the ti"insvei-se ])osition, the; fibi-es which are 

 in line with the direction of the curi-ent (jii th(! anode side of 

 the body should iK.t conti-act. if the filn-es fullilbng tliese 

 conditions as to location and o]-ientati(ni (the circular system) 

 do contract, they will cause the anterior end to be turned 

 towards the kathode and the anode side to become convex, — 

 in other words, produce the actually observed result. The 

 fibres of the longitudinal system sliould not be affected, and 

 there is no evidence; that they are. This explanation assumes 

 that the current produces its effect by directly causing the 

 contraction of prf)perly oriented rnuscle-fibres, possibly, or 

 even probably, witlujut relation to the stimulation of any 

 sense-organs of the aniniiil. Or, to ]nit it in another way, the 

 responses according tfj this view might not necessarily be 

 reactions of the oi-ganism at all, in tlie sense of being some- 

 thing that the animal does after receiving and transfoi-ming 

 a stimulus, but are direct effects of the stimulus acting on the 

 motor organs. It has doubtless occurred to the reader tliat 

 another explanation is possible for these reactions, namely, 

 that they are in no way essentially different from what would 

 be produced if the animal were given strong mechanical 



