136 



PRINCIPLES OF VETERINARY SURGERY 



in the form of slender, slightly-curved rods with round ends, 

 1.5 ju. to 3.5 ;u long by 0.2 /j. to 0.5 /* thick. 



Cultivation. — The best method of obtaining a specimen 

 of the bacillus is to inoculate an experimental animal with 

 the pus of a lesion or human sputum, and then after the dis- 

 ease has developed, destroy it and make cultures from some 

 of the tuberculous glands. It is cultivated with blood serum, 

 dogs' blood serum, potato, and egg. The tubercle bacillus 

 can be accustomed to grow on very simple media containing 

 no albumen. It can be grown on glycerin containing car- 

 bonate of ammonia, phosphate of potash, and sulphate of 



Fig. 13. 

 Ray Fungus. 



magnesium, in considerable quantities. It is in a mixture 

 of this character that Koch produced tuberculin. 



It grows best in a temperature between 85" to 105° Fahr. 

 and is exceptionally sensitive to extremes. It is killed at 

 165" F. It requires oxygen, but no light. Sunlight kills it 

 promptly. 



Staining. — The bacillus tuberculosis is difficult to stain, 

 and when stained is as difficult to decolorize, which char- 

 acteristic, once confusing, is now used as a valuable means 

 of differentiating it from other forms that take stains 

 promptly, and are easily decolorized with mineral acids. The 



