THE MUSCULARITY OF ARTERIES. 211 



at the same time that they form a firm texture. Although 

 arteries thus appear essentially different from muscles in their 

 hardness and their elasticity, as well as in their 'general texture, 

 they are considered, by a great majority of anatomists, as 

 partaking more or less of a muscular structure. 



In the human subject their structure is very difficult of 

 demonstration, and great differences exist in the accounts which 

 are given of it, even by anatomists who agree in the general 

 sentiment that the arteries are muscular. 



Thus, Haller believed that muscular fibres were most abun- 

 dant in the large arteries, while J. Hunter thought the reverse. 



Hunter appears to have investigated this subject with great 

 attention, and supposed the muscular substance, in the compo- 

 sition of arteries, to be interior, and the elastic niatter exterior ; 

 that in large arteries this muscular substance is very small in 

 quantity, and gradually increases in proportion as the artery 

 diminishes in size. He, however, observes, that he 7iever 

 could discover the direction of the muscular Jibres.* 



When the great talents of Mr. Hunter as an anatomist are 

 considered, this circumstance cannot fail to excite a belief that 

 the existence of these fibres is not certain : and if to this be 

 added the fact, that even the red-colored substance of the 

 arteries is elastic, and in that respect different from muscular 

 substance, the reasons for doubting must be increased. 



Bichat appears to have entertained very strong doubts on the 

 subject ; but he stands almost alone ; for a large number both 

 of the preceding and contemporary anatomists, seem to have 

 adopted the sentiment, that the arteries have a muscular 

 structure. 



The student of anatomy can very easily examine this 

 subject himself, by separating the coats of arteries into different 

 lamina ; and by viewing the edges of the transverse and 

 longitudinal sections of those vessels. While thus engaged 

 with this question, he will read with great advantage what has 

 been written upon it by Mr. Hunter, in his treatise on the 

 blood, &;c., (see chapter second, section 3.) Bichat ought also 

 * Treatise on the Blood, &c., vol. i. p. 113. Bradford's edition. 



