TUBERCULOSIS. 259 



that it soon leads to indurative cicatricial processes. This 

 great variability in the anatomic alterations induced by the 

 tubercle-bacilli explains the difference in the point of view 

 taken by the pathologic anatomist and by the clinician in 

 part with regard to tuberculosis. The anatomist, in de- 

 scribing the various processes, undertakes to separate them, 

 in spite of their common etiology, while to the clinician 

 the etiologic standpoint is alone productive, and therefore 

 decisive ; and he considers all diseases tuberculous in whose 

 products tubercle-bacilli can be demonstrated. 



Susceptibility of Human Beings to Tuberculosis 

 (Predisposition). Tubercle-bacilli are widely distributed 

 throughout the inhabited world. About one-seventh of 

 mankind is attacked by tuberculosis. The susceptibility 

 of human beings to the disease is, therefore, not especially 

 great. This view receives strong support from the obser- 

 vation that has now been repeatedly made that the bron- 

 chial glands of apparently healthy persons dying suddenly 

 by accident contain living and virulent tubercle-bacilli 

 (Loomis, Pizzini). In these cases the bacilli have passed 

 the lungs without giving rise to disease. From the ana- 

 'tomic-bacteriologic point of view such individuals in perfect 

 health as harbor tubercle-bacilli in the bronchial glands 

 or in some other part of their body may be designated 

 tuberculous ; while from the clinical standpoint only those 

 may be considered tuberculous that exhibit the clinical 

 manifestations of tuberculosis. 



From these observations the significance of the general 

 predisposition to tuberculosis must be clear. It is evident 

 that only a healthy and resistant body may harbor the 

 bacilli without danger, whereas every debilitating influence 

 facilitates the proliferation of the bacilli within the body. 

 The time of invasion by the bacilli and the appearance of 

 the disease do not always coincide. Only a poorly nour- 

 ished organism enfeebled by grief and worry or by pro- 

 tracted disease will suffer immediately after the entrance of 

 the bacilli. A special predisposition is conferred by the 

 abundance of sugar in the tissues in cases of diabetes. Not 

 rarely contusions of the lung determine the mobilization 

 of previously latent tubercle-bacilli (traumatic tuberculosis). 

 Resistance to invasion by the bacilli appears to be 

 strengthened in human beings by elevated climates. Ele- 

 vations of above 2000 meters (6500 feet) are measurably 



