98 ANIMAL-SENTIENT FORCES. [i. 



portance, that we make this distinction as clear as possible ; 

 and to this end, we must assume^ — what will be demonstrated 

 in another part of this book for the first time, namely, — 

 that the external impressions on the nerves (nerve-feeling, § 32), 

 becomes itself an animal motive force, before it reaches the brain, 

 and develops external sensations therein. The most certain 

 answer to the question, whether a movement, excited in a me- 

 chanical machine by the external irritation of a nerve, be simply 

 an action of the external impression (feeling), or whether it 

 result from an external sensation, is found in the experiment 

 of repeating the irritation, of which the movement is the result, 

 after the nerve is cut off from connection with the brain ; or, for 

 greater security against sympathetic action, after the head of 

 the animal has been separated entirely from the body. So 

 long as traces of animal life remain after this separation, the 

 same movement results from irritation of the nerve, although 

 the external impression is no longer propagated to the brain, 

 and no longer able to excite a material sensation therein ; con- 

 sequently, the movement cannot be a sentient action caused 

 by the external sensation, but is an animal action produced by 

 the motive force peculiar to the external impression. When 

 after this demonstration, the apparently sentient actions of 

 external sensations in the animal machines are investigated, 

 it is found, that the animal motive force of unfelt external 

 impressions can produce, although somewhat less perfectly, the 

 greater number of these movements, which we consider as 

 being solely sentient actions resulting from external sensations, 

 and which are in fact sentient actions also, as will be shown in 

 the second division of the work. 



183. The movements developed in organisms by the pe- 

 culiar animal moving force of the nervous system, not being 

 at the same time an animal-sentient force (6), are termed 

 nerve-actions i to distinguish them from sentient actions; con- 

 sequently, the movements excited in organisms by the motive 

 force of an unfelt external impression, are nerve-actions. The 

 majority of the sentient actions in mechanical machines of 

 external sensations are, therefore, at the same time, nerve- 

 actions (182); and the following propositions must be rejected 

 as erroneous. 1, That an animal movement in the mechanical 

 machines, which is a sentient action of external sensations, is 



