138 THE MORE CHRONIC INFECTIOUS DISEASES 



persons, and therefore they more easily contract the disease 

 from the surroundings contaminated by ill parents. 



Disinfection. To disinfect material from the tuberculous 

 individual it is necessary to collect it in some manner, 

 permitting burning or the action of chemicals over a long 

 time. Tuberculous sputum is best received in cardboard 

 boxes enclosed in a tin cup. The boxes are burned, and 

 the tin cup washed in 5 per cent, carbolic acid at frequent 

 intervals. If the person expectorate into cloths they should 

 be burned or soaked in 5 per cent, carbolic acid for at 

 least six hours. If neither of these methods is used ex- 

 pectoration should be received in a bowl or pot contain- 

 ing 5 per cent, carbolic acid or lime solution; the latter is 

 a cheap, simple and very efficacious disinfectant for all 

 tuberculous matter. Feces and urine should be received and 

 well mixed into the same solutions. After death from tuber- 

 culosis the room and all contents should be disinfected with 

 formaldehyde gas. 



Diagnosis. The most important means of diagnosis is 

 by finding the tubercle bacillus. To do this, the sputum 

 urine, feces, pus, exudate, or a piece of tissue is taken, stained 

 by special methods, or injected into guinea-pigs. The 

 material to be examined is spread on glass slides and stained 

 by a special technic. The tubercle bacillus, because of the 

 presence of waxy and fatty matters in it, stains with difficulty 

 and when once stained cannot be decolorized by acid or 

 alcohol, for this reason being called an acid-fast organism. 

 In order to stain the rod it is customary to use a chemical, 

 called a mordant, to assist the staining material in pene- 

 trating; these mordants are usually carbolic acid and anilin 

 oil. The dye is usually fuchsin, imparting a red color to the 

 organisms. After staining, a decolorizing solution is applied 

 to the preparation and all but the tubercle bacilli are de- 

 stained, leaving red bacilli, which are easily distinguished 

 under the microscope. 



Sometimes the germs are present, but cannot be found by 



