190 ON TIIK X.VITKK AND PRINCIPLES OF 



itself over the whole body. But when a person 

 starts at once from a state of perfect repose to the 

 performance of some feat requiring great and con- 

 tinued muscular exertion, various distressing and 

 inconvenient phenomena immediately result. Under 

 such circumstances the violent palpitation and tumul- 

 tuous action of the heart, the painful distension felt 

 in the cardiac region, and the unnatural pulsation of 

 the large arteries, without any corresponding dis- 

 order of the circulation through the small arteries 

 and capillaries, sufficiently evince the existence of a 

 morbid accumulation of blood in the great arterial 

 trunks. And the hurried panting respiration, and 

 occasional expectoration of blood (if the person be at 

 all plethoric), show that the pulmonary circulation is 

 similarly affected. The difficulty which the blood 

 thus experiences in passing from the aorta into the 

 smaller arteries is evidently occasioned by the re- 

 sisting contractility of the capillary vessels ; but as 

 the same cause operates in the production of deter- 

 mination of blood, it may be most advantageously 

 considered when speaking of the analogous disorder 

 of the circulation through the smaller arteries. 



Of those causes of an increased lateral pressure of 

 the aortic blood which act by diminishing the efflux 

 from the arterial system, the sudden application of 

 cold to the extremities and surface of the body is 

 perhaps the most frequent. And the contraction of 

 the innumerable cutaneous capillaries, which we wit- 

 ness as its immediate effect, by rendering those 

 vessels incapable of transmitting the usual quantity 

 of blood, must necessarily cause an accumulation of 



