xviii INTRODUCTION. 



Though muscles ordinaiily are red, colour is not essential to 

 them : it is entirely dependent on the blood contained in their 

 vessels, some being- naturally white or colourless, like what we 

 find them in almost all fish, and many birds. In general, mus- 

 cles possess bulk correspondent to their power, and are so 

 shaped and positioned as to have full effect in regard to the func- 

 tion they have to perform; while in their situations they confer 

 upon the body beauty of outline, combined with exquisite sym- 

 metry of form. In number we compute them at about three 

 hundred and twelve. And when we come to reflect that most 

 of them are susceptible of varied action, and to calculate to what 

 extent these actions niay be nniltiplied by different combinations, 

 vve shall not feel so much surprise at the endless multiplicity 

 and diversity manifested in the motions of the body. From what 

 has been said, therefore, it appears that the muscles are the 

 active or essential agents of locomotion; the bones, the passive 

 part of the apparatus : the two chief ends of locomotion being, 

 to enable the animal to obtain food, and avoid such objects as 

 may seem anywise offensive or detrimental to him. 



With few exceptions, muscles are distributed over the body in 

 pairs, or fellows, there being an equal number of correspondent 

 magnitude and power ranged on either side. And their positions 

 and attachments are such as to enable them to act as antagonists 

 one to another, either direct or indirect, singly or in combination : 

 the grand secret furnishing us with the explanation of the vast 

 variety of motion, internal as well as external, of which the body 

 is capable. 



The generality of muscles are furnished with what are called 

 tendons or sinews ; which, being composed of a material me- 

 chanically stronger than the flesh itself, but much less bulky, 

 serve the useful purpose of connecting the muscles to the part 

 to be moved, without at the same time proving an incumbrance 

 from their volume. In texture, they are dense, tough, and 

 fibrous ; and in aspect have a glistening blueish-white hue, form- 

 ing a beautiful contrast with the florid red of the fleshy por- 

 tion of the muscle. 



There is yet another part belonging to the muscular appara- 

 tus ; one that answers the same purpose that the synovia or joint- 



