CHAPTER THIRD. 



ON THE MUSCULAR SYSTEM, OR ACTIVE ORGANS OF 

 MOTION. 



FIRST SECTION. 



General Observations on the Muscular System. 



THE movements of animals are effected by the muscular 

 system, the most remarkable and essential property of 

 which is the power of contracting with rapidity and force 

 on the application of stimuli. The fibrous structure is not 

 a constant character, nor essential to the irritability of this 

 system, although that vital property is greatest in all the 

 higher classes, where this structure prevails. These irri- 

 table fibres appear to consist of lineal aggregates of fibri- 

 iious globules, the union of which is most intimate where 

 the contractile power is greatest. The cohesion of these 

 globules is least where all lineal arrangement is lost, in the 

 lowest tribes of animals, in which the slowly irritable fleshy 

 substance appears as a soft, homogeneous, cellular tissue. 

 The muscular system effects all the locomotions of animals, 

 and all the movements of their organs of relation, and forms 



