144 MICROBES AND HEALTH. 



cles is the same as would surround a bullet or any other 

 foreign body that might enter the lungs. The same 

 condition is present with every abscess. The zone of 

 new tissue which surrounds the tubercle or abscess 

 constitutes the battle line; it is the struggle between 

 the living and the dead. The same conditions are pres- 

 ent in gangrene. It has been stated that a dead cell 

 forms the center of a tubercle by exciting inflamma- 

 tion around it; also, that dust aids in producing con- 

 sumption. Dust may also aid in producing tubercu- 

 losis. When the vitality of the lung tissue is at a low 

 ebb, as descrbed, a small portion of dust from the mill, 

 the factory, or that furnished by the stone cutter or 

 iron worker, may lodge in an air cell and form the 

 nucleus of a tubercle. Here, again, this class is more 

 liable to this disease. 



Gases arising from low land, bad air, poor ventila- 

 tion, lack of sunshine and exercise also aid in produc- 

 ing consumption. 



Besides the reasons already given for consumption, 

 Doctor Thomas J. Mays, A. M., M. D., professor of 

 diseases of the chest in the Philadelphia Polyclinic, 

 visiting physician to Eush hospital for consumptives, 

 etc., and recognized as one of the most able men in the 

 profession, says in his 1901 treatise on consumption and 

 pneumonia, that any pressure upon the nerves which 

 supply the lungs, pressure from an enlarged artery 

 (aneurism), pressure from a tumor, any inflammatory 

 swelling, or pressure from enlarged glands may cause 

 consumption. 



The lungs are supplied by two nerves which have 



