i 



150 ANIMAL-SENTIENT FORCES. [i. 



paniment of various pleasures of the senses (250). Its sen- 

 sational stimulus is an agreeable external sensation, resembling 

 titillation, about the diaphragm, which originates from the 

 vital movements being altered by a vivid feeling of pleasure, 

 particularly of the senses (titillation, § 80). Sensational stimuli 

 to laughter result from everything which excites this sensation 

 at the diaphragm, even by flatulency of the stomach. The 

 instinct is manifested by the well-known contractions of the 

 diaphragm and thoracic and facial muscles, and its gratification 

 is actual laughter. Further, to this class belong other move- 

 ments, as the migration and hybernation of animals, the acts of 

 cleaning, bathing, swimming, pluming, revolving; the seeking 

 the sun^s rays and a warmer climate, the manufacture of clothing 

 which many animals undertake (as in forming cocoons), the 

 preparation of habitations, the establishment of republics 

 amongst beavers, bees, and ants, if we presuppose that these 

 animals all think. All these follow the laws of the primary 

 instinct for bodily movement, and have all as a basis, certain 

 obscure pleasant or unpleasant sensations, whereby the animal 

 is induced to attempt certain movements without knowing the 

 ulterior object to be gained, but which, according to the plans of 

 nature, are actually accomplished with the co-operation of 

 external impressions, for the purpose of securing the pre- 

 servation and well-being of the animal. 



285. It has not been to this day decided, whether the respi- 

 ratory movements are mechanical or volitional. Generally, 

 they are neither the one nor the other (Haller^s ^ Physiology,' 

 § 274), but manifestly the sentient actions of an instinct. So 

 soon as they are suspended, a distressing external sensation 

 arises in the chest, which is abhorred (280). This is the sen- 

 sational stimulus of the instinct of respiration, namely, the 

 strong desire to produce the opposite to this anxious state, 

 which we remember to be attained by respiring. The desire to 

 breathe consequently arises, the performance of which function is 

 the design of nature and the object of the animal in the instinct, 

 although of its further ends the animal is quite ignorant (266). 

 The sensational stimulus, namely, the unpleasant external sen- 

 sation, manifests its action on the vital movements (which are 

 the more widely influenced in proportion as it is excessive, § 271) 

 by a contra-natural and powerful beating of the heart (276, iv. 



