r 



. \A x 



\ f 



288 MANUAL OF BACTERIOLOGY. 



of syphilis (Lustgarten), and certain bacilli found in milk, 

 butter and cow-dung and on various grasses. All of these 

 may resist decolorization by acids or alcohol, and some 

 resist both. They must always be kept in mind in making 

 a diagnosis of tuberculosis. (See pages 44 and 295.) In 

 FIG. 8r. examining sputum it is particularly 



important to bear in mind that acid- 

 proof bacilli, resembling tubercle 

 . bacilli, have rarely been found in 



r cases of gangrene of the lung. 



They are likely to be longer than 

 > tubercle bacilli, and branch more 

 / often, besides being less resistant 



to decolorization. 1 The tubercle 

 Branching form of bacilli appear to owe their peculiar 



tubercle bacillus from a . . . f , 



staining properties to fatty sub- 

 culture. (X 1000.) l J 



stances contained in the bodies of the 



bacilli. In stained preparations the bacillus usually appears 

 very distinctly beaded, owing to the presence of stained areas 

 which alternate with unstained areas; these unstained areas 

 have been considered by some to be spores. 



The bacillus tuberculosis is aerobic. It is cultivated with 

 considerable difficulty, best at about 38 C. It does not 

 grow at a temperature below 29 C., and cannot therefore 

 be cultivated upon gelatin. It grows best upon blood-serum, 

 where the growth becomes visible in from ten to fourteen 

 days in the incubator. It forms a dry, mealy, scaly mass, 

 elevated above the surface, of a grayish-brown color. It also 

 grows upon glycerin-agar ; or glycerin-bouillon, on which 

 it forms a pellicle; upon potato; upon milk containing i per 

 cent, of agar and upon coagulated egg (see page 81). It 

 is important to have the medium moist. It can be cultivated 



1 Ophiils, Journal Medical Research, Vol. VIII., 1902; Ohlmacher, 

 Journal ^linerican Medical Association, 1901. 



