WILL. 587 



habitual concatenated movements being due to a series of 

 secondarily organized reflex arcs (Vol. I. p. 116). Tlie first 

 contraction is the one distinctly willed, and after willing it 

 we /let the rest of the chain rattle off of its own accord. 

 How now is such an orderly concatenation of movements 

 originally learned ? or in other words, how are paths 

 formed for the first time between one motor centre and an- 

 other, so that the discharge of the first centre makes the 

 others discharge in due order all along the line ? 



The phenomenon involves a ra23id alternation of motor 

 discharges and resultant afferent impressions, for as long a 

 time as it lasts. They must be associated in one definite 

 order ; and the order must once have been learned, i.e., it 

 must have been picked out and held to more and more 

 exclusively out of the many other random orders which 

 first presented themselves. The random afferent impres- 

 sions fell out, those that felt right were selected and grew 

 together in the chain. A chain which we actively teach 

 ourselves by stringing a lot of right-feeling impressions 

 together differs in no essential respect from a chain which 

 we passively learn from someone else who gives us im- 

 pressions in a certain order. So to make our ideas more 

 precise, let us take a particular concatenated movement for 

 an example, and let it be the recitation of the alphabet, 

 which someone in our childhood taught us to say by heart. 



What we have seen so far is how the idea of the sound 

 or articulatory feeling of A may make us say 'A,' that of B, 

 ' B,' and so on. But what we now want to see is lohy the 

 seTisation that A is lettered should make tis say ' B,' ivhy the sen- 

 sation that B is uttered should make us say '0,' and so on. 



To understand this we must recall what happened when 

 we first learned the letters in their order. Someone re- 

 peated A, B, C, D to us over and over again, and we imi- 

 tated the sounds. Sensory cells corresponding to each 

 letter were awakened in succession in such wise that each 

 one of them (by virtue of our second law) must have 

 ' drained ' the cell just previously excited and left a path by 

 which that cell tended ever afterwards to discharge into the 

 cell that drained it. Let S", S**, S*" in figure 89 stand for 

 three of these cells. Each later one of them, as it discharges 



