24 Dr. Young’s Lecture on the Functions 
on account of too great irritability, or never be emptied, from 
the weakness of its muscular powers. But the immediate 
effect of such a change as this, in the functions depending on 
the circulation, cannot be very material, and it can only be 
considered as an indication of a derangement in the nervous 
and muscular system, which is not likely to lead to any dis- 
ease of the vital functions. When the quantity of the blood 
transmitted by the heart is smaller than in health, the arteries 
must be contracted, until their tension becomes only adequate to 
propel the blood, through the capillary vessels, with a propor- 
tionally smaller velocity, and the veins must of course become 
distended, unless the muscular coats of the arteries can be 
sufficiently relaxed to afford a diminished tension, which is pro- 
bably possible in a very limited degree only. In this state the 
pulse must be small and weak, and the arteries being partly 
exhausted, there will probably be a paleness and chilliness of 
the extremities : until the blood, which is accumulated in the 
veins, has sufficient power to urge the heart to a greater ac- 
tion, and perhaps, from the vigour which it may have acquired 
during the remission of its exertions, even to a morbid excess 
of activity. Hence a contrary state may arise, in which the 
quantity of blood transmitted by the heart is greater than in 
perfect health ; the pulse will then be full and strong, the 
arteries being distended, so as to be capable of exerting a 
pressure sufficient to maintain an increased velocity, and to 
overcome the consequent increase of resistance ; a state which 
perhaps constitutes the hot fit of fever ; and which is probably 
sometimes removed in consequence of a relaxation of the ex- 
treme arteries, which suffer the superfluous blood to pass 
more easily into the veins. Such a relaxation, when carried 
