200 ANIMAL FORCES. [ii. 



then the power of sensation being restored, is inflamed in 

 consequence of the pain excited by the scourging, the inflam- 

 mation is a sentient action from an external sensation (207). 



iv. A nerve-action proceeding from an internal non-concep- 

 tional impression may be changed into a sentient action by 

 the addition of conceptional impressions, which act upon the 

 fibrils of the motor nerves conducting the impression itself 

 (130, 360). Thus, in convulsions proceeding from mechanical 

 irritants applied to the motor fibrils at their origin, or in their 

 course, or from worms in the stomach, the external impression 

 is not perceived, and the convulsions are simply nerve-actions 

 (162, 360); but if a fright, or pain, or other powerful external 

 sensation, be superadded, which also excites convulsions, but as 

 sentient actions by means of conceptional impressions, then 

 the convulsive paroxysm is re-excited by the latter as a sen- 

 tient action. In this way epileptic paroxysms, originally purely 

 nerve- actions, may be reproduced as sentient actions, by fear, 

 or pain, or other violent conceptions capable in themselves of 

 exciting convulsive attacks. 



V. An action may be both a nerve-action and sentient action 

 at the same time, if the causes of a change into one or the 

 other are superadded, as in the instances above mentioned, 

 yet neither ceasing to be what it was. If, after both 

 are excited, the causes of the one kind only cease, then the 

 other class remains (364). 



369. There naturally arises a question out of the preceding 

 considerations (362 — 368), as to the advantages which animals 

 endowed with mind and brain derive from their movements 

 being often at the same time both nerve-actions and sentient 

 actions, and produced by a twofold cause ; since in fact, mere 

 impressions without the co-operation of the brain or mind may 

 be sufficient to produce the animal functions, as in anencephalous 

 animals. Although this question has been noticed already 

 (184, ii), it requires further consideration here. 



370. To the end that an impression be felt, it is changed in 

 the brain into an internal impression (121, 129). But this 

 change of an external into an internal impression may take 

 place also by means of ganglia, or in some other way usual or 

 possible with animals ; only in such cases, the external impres- 

 sion will have no other reflex action in the animal machines 



