OF FISHES. 35 



MUSCLES; 



That prodigious mass of flesh enveloping the 

 bones, is regularly destributed in a way that is 

 both conducive to the protection of the vital ap- 

 paratus, and to the best mode of exerting muscu- 

 lar power. Like the cordage of a ship, every 



A DISSECTION OF THE MUSCLES OF THE JAWS, AND THE FIRST 

 TISSUE OF MUSCULAR FIBRES. UNDER THE SKIN. 



felt. The fact of this intervertebral substance being elastic, 

 has been taken advantage of by soldiers, who have often en- 

 listed themselves under a recruiting officer at night, when, 

 after being on their feet all day, the weight of the body, by 

 pressing down the intervertebral pieces, had made them 

 shorter. Thus, the next morning, after lying in a recum- 

 bent posture, the pieces recover their former thickness, and 

 the individual is an inch or more taller than the night be- 

 fore, when his height was measured. There is scarcely a 

 person that is not an inch taller in the morrrng than at night, 

 provided he has been exercising much on his feet, -through 

 the day. In old age, this substance looses its elasticity, and 

 hence aged people become crooked and unsteady in walking. 

 In fishes and serpents, no such change is ever effected by 

 age. 



