Chap. 10.] [ 139 ] 



CHAP. X. 

 STRUCTURE OF THE MUSCLES. 



General Defcription of Mufcles. Olfervaticns of the AbUe Fontana.-^ 

 OfLnvenboeck.Mufcfescompofed of fmall Fibres. StruSlurt o 

 different Mufcles. -Ant agonijls. Mufcles of the Fcetus* 



TH E bones, confidered with relation ,to the mo- 

 tions of the body, are merely levers ; let us now 

 confider the ftructure of the mufcles, which are the 

 immediate fources of all the motions of the animal 

 machine. 



The animal fubftance, which the anatomift calls 

 mufcle, is that which in common language pafles under 

 the name of the lean or flefh of meat. The colour of 

 the mnfcles, when they are firft removed from the 

 body, is red ; this colour, however, is not eflential to 

 them, but is merely owing to the prefence of blood, 

 for when mufcle is cleanfed from blood, it appears 

 white. In every recent mufcle we may at firft view 

 diftinguifh two kinds of fibres ; the one kind appears 

 red, and is the true mufcular fubftance; the other is 

 tendinous, has a white filvery appearance, and has no 

 power of contraction like the former. The tendinous 

 fubftance is fometimes collected ,into a cord, but is 

 very frequently expanded, fo as by covering the furface 

 of a mufcle, or by pervading its fubftance, to afford 

 a very extenfive connexion to mufcular fibres. 



The Abbe Fontana has taken great pains to examine 

 the ftructure of mufcles. He divided mufcular fubftance 

 with the point of a fmall needle till he came to minute 

 threads, which, whatever pains he took, would admit of 

 no further divifion. Thefe, he examined with a lens, 

 2 the 



