552 
A. O. ZWICK. 
says on this: The tubercle bacilli do not offer the resistance to 
physical and chemical agencies, especially not to high tempera¬ 
tures that is characteristic of true spore-forming microbes. 
One other fact concerning the tubercle bacillus, and then we 
will take up the transmisson of the germ by the circulating 
liquids of the body from a given point of entry, here the intes¬ 
tinal canal, to the point of attack, the lung frequently enough, 
showing that the former is easily possible, and the latter, as a 
consequence, probable. 
The bacillus tuberculosis is not able to multiply except in 
the interior of a living organism, for two reasons: In the first 
place it cannot grow except, or rather grows best, at the body 
temperature, the temperature of the blood; and in the second 
place it cannot elsewhere, except in the laboratory, find the suit¬ 
able culture media for its successful propagation. From this it 
results that the tubercle bacillus is an obligatory parasite which 
cannot thrive outside the animal economy, a fact of capital im¬ 
portance in the warfare against tuberculosis. That the appar¬ 
ently differing types of the tubercle organism—the avian, the 
mammalian, including the varieties of the bovine and the human, 
etc.—are merely adaptation forms to the different animal organ¬ 
isms with which the germ has to deal, I need not dwell on here, 
except to mention that this is merely added evidence of the ex¬ 
treme viability and adaptability of this germ to changing sur¬ 
rounding conditions of media, temperature, species of animal 
(host) and other vital requirements for its continued propaga¬ 
tion and existence, the dangers to the human race being increased 
by just so much as the germ is capable of thus adapting itself 
to its environment. It is a matter of fact, even, that the germs 
derived from many different patients, human beings, are not al¬ 
ways identical, varying in tenacity and resistance, and in degrees 
of virulence towards laboratory animals. 
Physiological Considerations .—The body fluids are the chyle, 
the lymph and the blood. The chyle is merely the name given to 
the lymph coming from the alimentary canal; it is lymph to which 
has been added some of the absorbed products of digestion. They 
