260 CLINICAL BACTERIOLOGY. 



free from tuberculosis. In the large cities of Mexico and 

 Pueblo, situated between 2000 (6500 feet) and 2500 meters 

 (8200 feet) above the level of the sea, tuberculosis is said 

 to occur but rarely, in spite of the density of the popula- 

 tion. 



Localization of Tuberculosis in Human Beings. In 

 human beings tuberculosis usually remains localized to the 

 lungs. Primary tuberculosis of other organs is rare in 

 adults. From the lungs, in the course of the disease, 

 propagation of the bacilli frequently takes place, partly, 

 through contact, to the pleura or other organs, partly, 

 through the intermediation of expectorated or swallowed 

 sputum, to the larynx and the intestine. In these organs also 

 the tuberculosis pursues the course of a localized disease. 

 The bacilli are carried by way of the lymph-paths and the 

 blood-stream to the membranes of the brain, the genito- 

 urinary apparatus, the bones and the joints, where they 

 also give rise to local disease. 



Highly febrile and rapidly fatal general tuberculosis 

 occurs when tubercle-bacilli gain entrance into the pul- 

 monary veins in large number, and rapid dissemination 

 through the whole body follows (miliary tuberculosis). 

 Under these conditions tubercle-bacilli can be found in the 

 blood. 



Mixed Infection. The symptom-complex of tubercu- 

 losis in human beings is at times quite materially changed 

 by the presence and proliferation of other microorganisms 

 in addition to the specific exciting agents. Especially in 

 pulmonary cavities is this almost regularly the case. In 

 the walls of such cavities sarcinae, streptococci, staphy- 

 lococci, tetragenus, the bacilli of blue pus, varieties of 

 proteus, and others, may lodge. There thus result septic 

 and pyemic disturbances that are foreign to the tuber- 

 culous process as such. Thus, the marked intermittent 

 fever observed in so many cases of tuberculosis is proba- 

 bly dependent principally upon the activity of streptococci 

 (streptococcus-curve). 



Occurrence and Distribution of Tubercle-bacilli. The 

 tubercle-bacilli are found especially in the lungs and in the 

 sputum in cases of pulmonary tuberculosis ; further, in all 

 tuberculous lesions, including lupus. The blood contains 

 the bacilli only in cases of general miliary tuberculosis and 

 then only in small number. Infection may take place 



