418 



MYCOBACTERIUM 



waxy substances, which are less permeable to cold than to warm aqueous solutions. 

 There is evidence that their resistance is more or less proportional to the amount 



S& *%• 



>^*rL^ 





Fig. 78. — Myco. tuberculosis — avian 

 type. 



Surface colonies of smooth and 



rough forms. Petrngnani p^^ 79.-Glycerine egg, 1 month, 37° C, show- 



medium, 7 weeks, 37 C. .^^^ j^^^^ ^^^^^^ ^^^^jlj. j,„anged in bundles. 



Smooth type of morphology. 



of waxy material present (Shen 1934). Use is made of this differential susceptibility 

 in isolating tubercle bacilli from contaminated material. Treatment of sputum, 

 pus, or other products, with 15 per cent, antiformin or 15 per cent, sulphuric acid 



♦ » 



t.ym. 



H V 



: i. 



V -H^ '^^ 





^%, 



t . 9 





T tf 



Fig. 80. — Glycerine egg, 1 month, 37° C, 

 showing fat ovoid forms arranged indi- 

 vidually and in groups. Smooth type 

 of morphology. 





'''> M 





<■ > '. 



Fig. 81.— Glycerine egg, 1 month, 37° C, 

 showing mostly short irregularly stained 

 rods, and cocco- bacilli, arranged singly, 

 in Chinese letter forms, and in dense 

 clumps. Rough type of morphology. 



for 5 to 20 minutes is often sufficient to destroy contaminating non-sporing bacteria 

 without killing the tubercle bacilli, which can then be cultivated on suitable media. 

 For the effect of relatively concentrated solutions of disinfectants reference may 



