98 
BACTERIOLOGY. 
Tubercles 
Toxins 
wall and lodge in the mesenteric glands. From this 
point they may be carried to remote tissues or organs. 
Cutaneous: The bacilli may enter the skin 
through injuries or abrasions, giving rise to the dis¬ 
ease known as lupus vulgaris. 
Once in the body, the tubercle bacilli may become 
localized in any tissue or organ, and there proceed to 
multiply. The result is the formation of a nodule or 
tubercle, from which the disease takes its name. The 
tubercles are about the size of a millet-seed, and at 
first are distributed separately in an organ. As they 
grow larger the central portion is poorly supplied with 
blood, so that it degenerates, softens, becomes cheesy, 
and finally may ulcerate. Tubercles that are placed 
close together may coalesce and go on to ulceration, 
causing large abscesses. If the tubercle bacilli reach 
the circulating blood they may be carried to many 
organs and tissues, at once causing a tuberculous sep¬ 
ticemia or miliary tuberculosis. In such cases at 
autopsy the miliary tubercles are found everywhere in 
the body. 
It is well to distinguish between the words “tuber¬ 
cular” and “tuberculous,” as they are often used in¬ 
correctly. The word tubercular means nodular and 
has no reference to the nature or cause of the nodule. 
Tuberculous, on the other hand, is an adjective used 
to indicate tissues infected with tubercle bacilli. 
The damage done in tuberculosis is due almost 
entirely to the absorption of the toxins formed by the 
tubercle bacillus. These are of two kinds: an extra- 
