GENERAL ANATOMY OF THE MUSCLES. 353 



parallel with them; they then divide and follow the course of 

 the smaller fasciculi; they divide and subdivide again after the 

 same rule, till they become mere capillary tubes, from which 

 the nutritive matter is exhaled. The veins accompany the 

 arteries, and receive their blood; some of them creep along the 

 surface of the muscle without having corresponding arteries. 

 Bichat says that they are injected with great facility from their 

 trunks, from which he supposes that their valves are less nu- 

 merous than in other parts of the system. 



The colour of the muscular fibre seems to be, in a measure, 

 independent of the blood which circulates in it. Some animals 

 with red blood have white fibres, as frogs. The colour of the 

 muscular fibre is not altered in animals that have been suffo- 

 cated. The muscular fibres of the intestines and of the bladder, 

 though abounding in blood vessels, are whiter than the muscles 

 of voluntary motion. 



Lymphatics have been injected in the intervals between mus- 

 cles and between their fasciculi. 



The Nerves of the muscles are large and abundant, as the 

 nerves of the brain and spinal marrow are chiefly spent upon 

 them. They are generally proportioned to the size of the mus- 

 cle which they have to supply, but there is some variety in this 

 respect. They accompany the arteries, and are united to them 

 by cellular substance. Their ultimate terminations are traced 

 with great difficulty, and there is consequently an uncertainty 

 in this respect. Before they disappear they become soft by 

 divesting themselves of their cellular envel >pe, and are supposed 

 to bring thus their medullary substance in immediate contact 

 with the muscular fibre. The recent observations of MM. Pre- 

 vost and Dumas, are thought to throw some light on this sub- 

 ject, and have been received with a very respectful attention. 

 They say, that by macerating in clean water, and in a dark 

 place, the muscle of a bullock, and then throwing a strong con- 

 centrated light upon it, the distinction of colour between the 

 nerves and the muscular fibres becomes very apparent. With 

 the aid of a microscope and a fine knife, the nervous ramifica- 

 tions may be thus traced. The trunk of the nerve enters the 

 muscle parallel with its fibres, and soon begins to give off, at 



30* 



