EASTERN COUNTIES VETERINARY MEDICAL ASSOCIATION. 379 
recovers so slowly that he is despondent at times of ultimate 
convalescence. 
I have said that infectious diseases can be taken by inhaling 
the germs floating in the air; nor can this be wondered at if we 
only contemplate the extremely delicate texture and intricate 
mechanism of the lungs, when we find that in ordinary breathing 
about twenty cubic inches, or two thirds of a pint of air enters the 
lungs of a man at each inspiration, that one or two thousand 
gallons of air are brought daily into contact with the blood, the 
whole of the blood in the body is presented to the air in the 
course of less than a minute of time. About one thousand times 
a day the air passes over those soft, flexible bags called air-cells, 
formed of a membrane T q 3 q ^th of an inch in thickness, not much 
thicker than the film of a soap bubble. The lungs of a full-grown 
person (physiologists inform us) contains 600,000,000 of them. 
.By a process of endosmosis the oxygen (and in all human proba¬ 
bility germs also) enter the blood ; they are at once embarked in 
a number of little vessels called red corpuscles ^^th of an inch 
in diameter. Physiologists tell us there are three millions of 
them in a single drop of blood. As to the minuteness of some of 
the organisms met with, I may mention that the organisms of the 
pollen of flowers which produce hay fever, are so small that it 
would require thirty-seven millions to weigh one grain, or six mil¬ 
lions of particles of pollen of our English meadow grass. These 
minute organisms and the white corpuscles of the blood are known 
to be capable of passing through the walls of the capillaries. 
Hacteria are germs that have become organisms, and are of 
different kinds. Some of them are so minute that they are beyond 
the reach of all sense, requiring a magnifying power of a thousand 
diameters. [Some of them have motion, some of them have no 
motion, some of them are oval in form, some rod-shaped, some of 
exquisitely delicate filamentous fungi, some contain the contagious 
virus, some do not. Spores are the foliage or bloom of the 
straight, rod-like bacteria. These cannot be originated by the 
normal tissues or juices; they must have been derived from the 
external air; they are found to exist in many parts of the human 
body, and in animals; never in the blood of healthy persons in 
life. These germinal matters in the air attach themselves to the 
particles of dust floating in it; particles scarcely visible in ordi¬ 
nary light appear as motes in the sunbeam or in the beam of an 
electric lamp. It is by the agency of these particles that they 
are conveyed from place to place. 
The numerous experiments conducted with vast care and 
exactness by Baron Liebig, Professor Tyndal, Professor Leister, 
Professor Roscoe, Mr. Pasteur, l)r. Burdon Sanderson, Dr. W. 
Roberts, of Manchester, and other men. The most advanced 
thinkers of the present day have proved, as I think most con¬ 
clusively, that the germ theory is a reality. They show most 
satisfactorily that if an infusion, or wet dead animal or vegetable 
matter, at a certain temperature be exposed to ordinary atmo- 
