THE PECULIAR FACULTIES 273 



special branch of the animal chain that has started afresh by spon- 

 taneous generation (Chapter VI., p. 247). 



The plainly marked and well-known muscular system in insects 

 is everywhere found afterwards in animals of the following classes. 



Feeling is a faculty which must take the fourth rank among those 

 that are not common to all living bodies ; for the faculty of feeling 

 appears to be still less general than those of muscular movement, 

 respiration and digestion. 



We shall see farther on that feeling is only an effect ; that is to 

 say, the result of an organic act and not a faculty inherent in any of 

 the substances, which enter into the composition of a body that can 

 experience it. 



None of our humours and none of our organs, not even our nerves, 

 have the faculty of feeling. It is only by an illusion that we attribute 

 the singular effect, that we call sensation or feeling, to a definite part 

 of our body ; none of the substances composing this part does or can 

 really feel. But the very remarkable effect called sensation or, when 

 more intense, pain, is the product of the function of a very special 

 system of organs, the activity of which is dependent on the circum- 

 stances which provoke it. 



I hope to prove that this effect, constituting feeling or sensation, 

 is an undoubted result of an affective cause which excites action in 

 any part of the special system of organs adapted to it ; this action 

 by a repercussion, that is swifter than light and affects every part of 

 the system, delivers its general effect in the common nucleus of sensation 

 and the sensation is then propagated to the point of the body that was 

 affected. 



I shall endeavour to describe in the third part of this work, the 

 wonderful mechanism of the effect which we call feeling : I shall here 

 merely remark that the special system of organs for producing such an 

 effect, is known under the name of the nervous system ; and I may add 

 that this system only acquires the faculty of giving rise to feeling, 

 when it is so far developed as to have numerous nerves meeting in a 

 common nucleus or centre of communication. 



It follows from these principles that no animal, which does not possess 

 a nervous system of the kind named, can experience the remarkable 

 effect in question, nor consequently can it have the faculty of feeling. 

 A fortiori, any animal which does not have nerves, terminating in a 

 main medullary mass, must be destitute of feeling. 



The faculty of feeling therefore cannot be common to all living 

 bodies, since it is universally admitted that plants have no nerves and 

 can therefore have no feeling. It has however been held that this 

 faculty is common to all animals ; this is clearly a mistake, for all 



