Contents xix 



CHAPTER II.— A SHORT Description of Muscles. 

 Also, What part of a Muscle Primarily Con- 

 tracts. 



On the fleshy fibres of muscles, p. 235. Description of 

 the fibrils, p. 235. They seem primarily to undergo con- 

 traction, p. 236. The oblique position of the fibres is less 

 fit for the contraction of the muscle, p. 236. But the posi- 

 tion of the fibrils is fitted for this, p. 236. The muscle is 

 drawn together by the contraction of the fibrils, p. 237. 

 The fibrils are eminently suited for producing the contrac- 

 tion of the muscle, p. 237. 



CHAPTER III.— Of the Particles by means of 

 WHICH Muscular Contraction is Effected ; and, 



IN THE first place, ON THE MOTIVE PARTICLES 



Brought by the Blood. Incidentally, of the 

 Structure and Use of Muscular Flesh. 



The contraction of a muscle is partly produced by the 

 animal spirits, p. 239. Also partly by certain particles 

 supplied by the blood, p. 239. The contraction of the 

 muscles promotes the motion of the blood, p. 239. For 

 what end that takes place, p. 239. The muscular flesh 

 seems destined for the secretion of motive particles from the 

 blood, p. 240. How the blood passes through the muscles, 

 p. 240. It does not seem to be extravasated, p. 240. It 

 is probable that the arteries and the veins are connected 

 with each other by certain special vessels, p. 241. On the 

 ruddy sediment of muscular flesh, p. 242. The motive 

 particles supplied by the blood seem to have a saline-sul- 

 phureous character, p. 242. Why animals become lean by 

 working, p. 243. 



CHAPTER IV.— The Animal Spirits by which 

 Muscular Contraction is Produced consist of 

 NiTRO-AERiAL Particles. Incidentally, as to 

 THE Motion of the Brain. 



Why the respiration is so much increased in violent 

 movements, p. 244. This does not take place in order that 



