212 PROOFS OF THE IRRITABILITY OF THE ARTERIES. 



to be read upon this subject, which he has discussed in his 

 Anatomic Gcnerale — Sijstcme Vasculaire a Sang Rouge, 

 article Troisieme, &c. ; and also in his Traite des Membranes 

 article Sixieme. 



The belief of the irritability of arteries does not, however, 

 rest upon the appearance of their fibres. 



1. It is asserted by very respectable authors,* that they have 

 been made to contract by the application of mechanical and of 

 chemical irritation, and also of the electric and galvanic power. 



2. A partial or local action of arteries is often produced by 

 the local application of heat and rubefacients, as has been 

 already observed. 



3. Arterial action is often suspended in a particular part by 

 the application of cold. It has also been observed that the arte- 

 ries have for a short time ceased to pulsate in cases of extreme 

 contusion and laceration of the limbs.f 



4. When arteries are divided transversely in living animals, 

 they often contract so as to close completely the orifice made by 

 the division. 



5. In a horse, bled to death, it was ascertained by Mr. Hun- 

 ter, that the transverse diameter of the arteries was diminished 

 to a degree that could not be explained by their elasticity. He 

 also found that, after death, the arteries, especially those of the 

 smaller size, are generally in a state of contraction, which is 

 orreater than can be explained by their elasticity : for if they 

 are distended mechanically, they do not contract again to their 

 former size, but continue of a larger diameter than they were 

 before the distension ; although their elasticity may act so as 

 to restore a very considerable degree of the contraction observed 

 at death. 



The contraction, which is thus done away by distention, 

 Mr. Hunter supposed to have been produced by muscular 



* See Soemmering on the Structure of the Human body, vol. iv. German 

 edition, Dr. Jones on the process employed by nature for suppressing 

 Hemorrhoge, Ace. 



t This local suspension of arterial motion by cold, Ace, applied locally, is 

 very difficult to explain: as the action of the heart and the elasticity of the 

 arteries appear sufficient to account for the pulsation of the large arteries. 



k 



