94 BACTERIOLOGY. 



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. 



Tubercles 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. 



Toxins The damage done in tuberculosis is due almost 



entirely to the absorption of the toxins fo'rmed by the 

 tubercle bacillus. These are of two kinds: an extra- 



