BACILLI IN CHRONIC INFECTIOUS DISEASES. 395 



keeping well. The staining is effected more quickly if heat is ap- 

 plied. The tubercle bacilli stain by Gram's method, but this is not 

 to be recommended for general use, owing to the fact that the pro- 

 toplasm of the rods is frequently contracted into a series of spheri- 

 cal, stained bodies, which might easily be mistaken for micrococci. 



The examination of sputum for the presence of the tubercle ba- 

 cillus is recognized as a most important procedure for the early diag- 

 nosis of pulmonary tuberculosis. It is at- 

 tended with no special difficulties, and every 

 physician should be acquainted with the 

 technique. 



The patient ehould be directed to expec- 

 torate into a clean, wide-mouthed bottle or 

 glass-covered jar the material coughed up 

 from the lungs, and especially, in recent 

 cases, that which is coughed up upon first 

 rising in the morning. This should be 

 placed in the physician's hands as promptly FIG. 117. Bacillus tubercuio- 

 as possible ; although a delay of some days f & ^ tum ' x 1 ' ooa> (Baum ' 

 does not vitiate the result, and the tubercle 



bacilli may still be demonstrated after the sputum has undergone pu- 

 trefaction. It is well to pour the specimen into a clean, shallow vessel 

 having a blackened bottom a Petri's dish placed upon a piece of dead- 

 black paper will answer very well. In tuberculous sputum small, len- 

 ticular masses of a yellowish color may usually be observed, and one 

 of these should be selected for microscopical examination, by picking 

 it up with a platinum needle and freeing it as far as possible from 

 the tenacious mucus in which it is embedded. If such masses are 

 not recognized take any purulent-looking material present in the 

 specimen, whether it be in small specks distributed through the mu- 

 cus, or in larger masses. A little of the selected material should be 

 placed in the centre of a clean cover glass and another thin glass 

 cover placed over it. By pressure and a to-and-fro motion the mate- 

 rial is crushed and distributed as evenly as possible ; the glasses are 

 then separated by a sliding motion. The film is permitted to dry by 

 exposure in the air. When dry the cover glass, held in forceps, is 

 passed three times through the flame of an alcohol lamp or Bunsen 

 burner to fix the albuminous coating. Too much heat causes the film 

 to turn brown and ruins the preparation. The staining fluid (ZiehFs 

 carbol-f uchsin) may then be poured upon the cover glass, or this may 

 be floated upon the surface of the fluid contained in a shallow watch 

 glass. Heat is now applied by bringing the cover glass over a 

 flame and holding it there until steam begins to be given off from 

 the surface of the staining fluid ; it is then withdrawn and again 



