ORGANIC MOVEMENTS 7 



dog's brain, but we may assume hypothetically, that other 

 lines of nerves have been used for carrying out what there 

 was to be done. In the third instance the change from 

 without affected the organs which perform the movement 

 itself, and this change was followed by a change in the use 

 of these organs : for it is clear that the work done in 

 walking by every single leg when there are four legs at the 

 disposal of the organism does not remain the same when 

 there are only three. 



Reviewing our three instances, we may say that in the 

 first case there was a variation in the totality of the 

 external stimuli, followed by a corresponding variation in 

 the effect, whilst such a corresponding variation followed a 

 change of the intermediate organs in the second case, and a 

 change in the general condition of the proper effectuating 

 organs in the third. We observe, then, a co-ordination of 

 our three instances to the three fundamental branches of 

 ordinary motor physiology already mentioned. It is not this 

 co-ordination, however, but the existence of something like 

 regulation in organic movement that interests us chiefly, 

 and here we have the starting-point of our future researches. 



All changes, whether in the external conditions, or in the 

 intermediate organs, or in the effectuating organs, may be 

 described as changes of motor stimulation in general, and 

 we may therefore say that the relation between motor stimuli 

 and movement as such is in fact our general problem. Are 

 there sums or aggregates on both sides or not ? If not, 

 what is there ? These are the questions we have to answer. 



Let us now review the great variety of actual organic 

 movements, with the object of discovering the kinds of 

 relation between cause and effect in every class. 



