552 
OBSERVATIONS ON THE 
course, arose from a compression of the capillaries of the 
lungs, or from their becoming twisted in a variety of ways. 
These mechanical theories, like every other mechanical 
theory which has been applied to vital action, did not 
stand their ground; but the fact remained unexplained, 
viz. that, after death by suffocation, the venous system is 
found gorged with blood, and that the obstruction to the 
blood's course seems to commence in the lungs. If this 
view be correct, the advantages to be derived from addi- 
tional reservoirs for the blood will be apparent ; and the 
fatal effects of suspended respiration may be perhaps in 
the ratio of the capacities of the two systems of vessels ; 
that is, if the veins be small in caliber, and few as to num- 
ber, the powers of the animal to suspend respiration will 
be proportionally feeble, and the distress arising from a 
suspension of respiration proportionally great. (The dis- 
tressing sensations occurring in suffocation I consider as 
chiefly owing to the accumulation of blood in the right side 
of the heart and in the head). On the contrary, if the 
venous system be capacious, and more especially if addi- 
tional reservoirs be annexed, capable of considerable dis- 
tension, as we find to be the case in some Cetaoea, in 
the beaver, and in the diving birds, as the duck tribe, 
then there will exist considerable powers of suspending 
respiration at will. Perhaps we may be allowed to illus- 
trate this speculation, by the fact, w^ll known to phy- 
sicians, that almost instantaneous relief follows the ab- 
straction of a few ounces of blood, in laborious respiration, 
occasioned by an obstruction to the passage of the blood 
through the lungs. The relief follows equally whatever 
may be the cause of the disease, whether an inflammatory 
point in the organ itself, or a watery or mucous effusion, 
causing obstruction. 
If we consider the distribution of the blood in the abdo- 
