J SENSORIAL ACTIONS. Seer. XI. 



2. There are many motions of the body, belong- 

 ing to the irritative elafs, which might by a hafty 

 obferver be miftaken for aflbciated ones ; as the pe- 

 riftaltic motion of the ftomach and inteftines, and 

 the contrasclrons of the heart and arteries, might be 

 fuppofed to be aflbciated with the irritative motions 

 of their nerves of fenfe, rather than to be excited 

 by the irritation of their mufcular fibres by the dif- 

 tention, acrimony, or momentum of the blood. 

 So the diftention, or elongation of mufcles by 

 objects external to them irritates them into con- 

 traction, though the cuticle or other parts may 

 Intervene between the ftimulating body and the 

 contracting mufcle. Thus a horfe voids his excre- 

 ment when its weight or bulk irritates the rectum 

 or fphincter ani. Thefe mufcles act from the irri- 

 tation of diftention, when he excludes his excre- 

 ment, but the mufcles of the abdomen and diaph- 

 ragm are brought into motian by aflbciation with 

 thofe of the fphincler and rectum. 



SECT. XII. 



OF STIMULUS, SENSORIAL EXERTION*, AND FIBRQU& 

 CONTRACTION. 



I. Of fibrous contraction, i. Two particles of a Jibre 

 cannot approach without the intervention offomething, 

 as in magnet if in, elelricity+ elajlicity. Spirit of life 

 is net ekftric ether. G ah ant's experiments. 2. Con- 

 traftion of ajibre. 3. Relaxation fucceeds. 4. Sue- 

 ceffi've contractions, with intervals. Quick pulfe from 

 debility ) from paucity of blood* Wak contractions per- 

 formed 



