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the multiplf ing tubercle bacilli invading the tissues around 

 the tubercle. As a rule extension of the disease from the 

 primary focus takes place by way of the lymphatic vessels 

 and glands — the lymph carrjdng the germs. In old and 

 severe cases, where a large amount of tissue has been de- 

 stroyed by the invading germs, the tubercle bacilli may be 

 carried from the primary tubercle to other parts of the body 

 by the current of blood in the blood vessels. 



LOCATION OF THE TUBERCLES AS DETERMINED BY POST-MORTEM 



EXAMINATIONS. 



No tissue or part of the body is exempt from the ravages 

 of this disease. Some tissues and organs, by virtue of their 

 structure, use and location, are more exposed to the action 

 of tubercle bacilli, and consequently are more frequently 

 the place of lodgement and growth of these germs than other 

 parts of the body. Other organs appear to possess, by lo- 

 cation and function, a comparative immunity and are rarely 

 the seat of tubercles. The most frequently attacked tissues 

 and organs will be given in regular order. 



(a) The lungs are most frequently the location of tuber- 

 cles. When the individual has tuberculosis of the lungs he 

 is said to have consumption or pulmonary tuberculosis. 

 "When the lung tissue is first invaded it may be filled with 

 small, hard nodules, which are called miliary tubercles. In 

 exceptional cases these miliary tubercles do not increase in 

 size. As a rule, they increase in size until those near one 

 another unite and form large, soft, yellow, cheesy masses. 

 Unusually a fibrous capsule develops around this mass to 

 protect surrounding tissue and prevent its eruption into the 

 bronchial tubes. Occasionally this yellow tuberculoiis mass 

 erupts into the bronchial tubes; is coughed up and dis- 

 charged into the outer world by expectoration. No one part 

 of the lungs is more liable to be involved than the others, 

 and the various stages in the development of tubercles may 

 be seen in one tuberculous lung. The Bureau of Animal 

 industry states that their records show that the large caudal 

 lobes of the lungs were most frequently tuberculous. The 



