96 
J. CAMPBELL. 
while in venous blood the proportions are materially changed ; 
here we find the proportions about one to four, showing a large 
increase of carbon dioxide. 
The venous blood, in its passage through the pulmonary 
circulation, gives off its carbon dioxide and receives a fresh sup¬ 
ply of oxygen ; this new supply of oxygen is in the general cir¬ 
culation given up to the tissues, for the purpose of supporting, 
strengthening and building up any destroyed and broken-down 
part of the economy that may exist. This process of building 
up and tearing down is a continuous process, beginning with 
life and only ending with death. Therefore, any condition 
which will interfere with a full normal supply of oxygen being 
received by the economy will result in disease. So also im¬ 
peded or retarded metamorphosis will mean the same thing— 
disease. 
Fully realizing and understanding the above conditions, we 
are better prepared to combat disease, which is the result of the 
derangements of some of the conditions before stated, which 
may be aggravated by the existence of some specific germ of 
disease. 
Take an average man in good health weighing 160 pounds, 
with moderate exercise in the open air during the day, he will 
absorb into the blood, during its passage through the pulmo¬ 
nary circulation, 160 gallons of oxygen from the air; to obtain 
this amount of oxygen he is obliged to inhale about 5000 gal¬ 
lons of air; 4000 of it being nitrogen and 1000 oxygen. The 
amount inhaled varies very considerably, depending on condi¬ 
tions—the amount of exercise taken, etc. But for practical pur¬ 
poses, we will assume that from 10 to 20 per cent, of the oxygen 
inhaled into the lung is utilized by the blood, which will give 
us very close to one gallon of oxygen for each pound the man 
weighs; this will be the normal supply for 24 hours. With 
that amount of oxygen absorbed by the blood in its passage 
through the lungs, in addition to what may be utilized through 
the stomach, etc., the man will retain a normal amount of 
health. 
