134 ANALYTIC SECT, XVII. 
ccexx1. During inspiration, a certain pro- 
portion of pressure must be removed from the 
periphery of the pulmonary arteries, by the 
inflation of the lungs; it may therefore be pre- 
sumed, that the motion of the blood in them 
should then be freer than during expiration. 
This conclusion is disputed by Bichat: “ I have 
proved,” says he, “ that the state of fulness or emp- 
tiness of the stomach, and of all the hollow organs 
in general, brings no apparent change into their 
circulation ; that, consequently, the blood passes 
through the vessels folded on themselves, as when 
they are distended in every sense.” ‘The same 
author asserts, that by exhausting the air from 
the lungs of a dog, and opening the carotid 
artery at the same moment, the blood flows as 
freely as when the lungs continue their function. 
Collections of fluids in the thorax, have again 
and again been urged in support of the same 
opinion. 
cccxxIv. But these objections, it may be urged, 
are none of them very conclusive. It does not 
appear certain, that an accurate estimate of the 
circulation of the lungs can be formed, by gauging 
with the eye the jets of blood from the carotid 
artery. It is not true, that the expansion of hollow 
organs have no influence on their arteries. The 
pudic artery is materially affected by the expan- 
sion of the penis; the arteries of the womb, also, 


