112 ESSENTIALS OF BACTERIOLOGY 



ordinary agar-peptone medium, Nocard and Roux obtained a 

 culture-medium upon which tubercle bacilli grow much better 

 than upon blood-serum, especially after once obtained in 

 pure culture. Bits of tissue are placed on the surface, not 

 rubbed in until after several weeks ; then gently crushed and 

 spread over surface; this hastens growth. 



Stroke cultures are used as with blood-serum. They 

 are placed in incubator after inoculation, and remain there 

 about ten days, at a temperature of 37 C. The cotton plugs 

 of the tubes are covered with rubber caps, the cotton first 

 having been passed through the flame, and moistened with a 

 few drops of sublimate solution. The rubber cap prevents 

 the evaporation of the water of condensation, which always 

 forms and keeps the culture from drying up. 



The growth which occurs resembles the rugae of the stom- 

 ach, and sometimes looks like moistened crumbs of bread. 

 The impression or "Klatsch" preparation shows under the 

 microscope a thick, curled-up center around which threads 

 are wound in all directions. And these fine lines show the 

 bacilli in profusion. 



Potato. It can be cultivated on slices of potato which are 

 placed in air-tight test-tubes to which glycerin has been added. 



Bouillon. Bouillon containing 4 per cent, glycerin is a 

 very good medium. Growth on the surface only. 



Pure Cultures from Sputum. Kitasato recommends the 

 thorough washing, changing the water ten times, of the small 

 masses found in the sputum of tuberculous persons. When 

 such specimens are examined, they show tubercle bacilli 

 alone, and when inoculated in agar, give rise to pure cultures. 



Animal Inoculation for Diagnosis. When the bacilli are so 

 few in number in sputum or urine as to make their detec- 

 tion difficult, and also when doubt exists as to the identity 

 of acid-fast bacilli found, several guinea-pigs should be in- 

 jected in the groin and smears and sections made from the 

 enlarged glands resulting. 



Varieties. Branching and other aberrant forms are not 

 rare, and the tendency now is to class the organism with the 



