MUSCULAR MOTION. 355 



in the extremities. In monstrous foetuses it sometimes hap- 

 pens that the muscular system is either wholly or partially 

 supplanted by adipose matter and by infiltrated cellular sub- 

 stance. 



CHAPTER II. 



ON MUSCULAR MOTION. 



THE muscles, after death, are soft, easy to tear, and have 

 but little elasticity; it is only during life that they manifest such 

 extraordinary strength, and retain their powers of motion. 

 The general phenomena of the latter have been happily ex- 

 pressed by the word myotility, suggested by M. Chaussier. 

 These phenomena are, contraction, elongation, and, according 

 to Barthez, a power of remaining motionless or fixed. 



In contracting, the muscle shortens, swells and becomes 

 hard; presents wrinkles on its surface; and its fibres are some- 

 times thrown into a state of oscillation or vibration, from their 

 alternate relaxation and contraction. It is owing to the vibra- 

 tory motion in the fibres of a muscle, during their contraction, 

 that a rustling is heard on the application of the stethoscope to 

 them. The hollow, distant rumbling, when the meatus exter- 

 nus is closed by the finger, is owing to the same vibration in 

 the muscles of the finger employed. This is readily proved by 

 the following experiment: close the meatus with the end of the 

 handle of an awl or a fork, pressed against it by the finger, and 

 it will be found that the muscular vibrations are continued 

 along the instrument: plant, afterwards, the point of the instru- 

 ment upon a soft, inelastic substance, so as to make, in that 

 way, the closure of the meatus, and the rumbling will instantly 

 cease. The roaring noise of sea-shells may be explained In 

 the same way. The colour remains the same, which proves 

 that there is not an appreciable addition to the quantity of its 

 circulating fluids. The rapidity with which this contraction 

 may take place, is manifested in speaking, in running, and in 

 playing upon a stringed instrument; and its strength, by the 

 immense burdens that some individuals can raise and bear, 



