An exposition of the principles of pathology, and of the treatment of diseases / [Daniel Pring].
- Pring, Daniel, 1789-1859.
- Date:
- 1823
Licence: Public Domain Mark
Credit: An exposition of the principles of pathology, and of the treatment of diseases / [Daniel Pring]. Source: Wellcome Collection.
129/532 page 113
![overcome. If such is the fact, the covering of an artery may be essential to its contraction, by re¬ straining the dilatation of it by the blood, within bounds which are compatible with the exertion of the contractile power of its muscular coat. I have elsewhere^ suggested that, even sup¬ posing an artery to possess no power of con- traction and dilatation in itself, yet, as it is kept in a forced state of distention, it would contract and dilate by the mode of circulation of tlie heart alone, which impels blood into the arteries in suc¬ cessive quantities. 1 have argued that, as the volume of blood must be greater in a given space of an artery at one time than at another, so the calibre of the artery must be proportionally in¬ creased. To this Dr. Parry has replied*]*, by ob¬ jecting to the proof that an artery contains more blood at one time than at another; a supposition which certainly arises very naturally out of the manner in which the heart alternately receives , blood, and expels it again into the arteries. Dr. Parry, however, denies tliat the quantity of blood is on this account greater in a given space of an artery at one time than at another; but he admits “ that the velocity is greater:” a concession which will answer the purpose of my argument equally well; for an alternate increase and reduction of the velocity of the blood would occasion alternate states of contraction and dilatation of the vessel which con- * View of the Relations of the Nerv'ous System. f On the Arterial Pulse, p. 120. ' I](https://iiif.wellcomecollection.org/image/b29313752_0129.jp2/full/800%2C/0/default.jpg)
