1893.] MICROSCOPICAL JOURNAL. 295 



BACTERIOLOGY. 



Examination of Sputum for Tubercle Bacilli : Biedert's 

 Method. — The object of this is to find the tubercle-bacilli when 

 they are present in the sputum in small numbers. In 1886, 

 Biedert (Bed. klin. Wocheaschrift, 1886, No. 42, p. 43) called at- 

 tention to the fact that smearing the crude sputum on the cover 

 glass and staining the same does not give accurate results, so 

 far as detecting the number of bacilli is concerned. This is due 

 to the fact that clumps of sputum that usuall}^ contain a larger 

 number of tubercle-bacilli than the more liquid portion are so 

 deeply stained as to obliterate their presence. In order to re- 

 duce the sputum to a more homogeneous consistency and at 

 the same time to concentrate into a small mass, the bacilli in a 

 larger quantity of sputum, Biedert mixed the sputum with 

 twice its volume of a 2 per cent solution of caustic potash «)r 

 soda (soda being preferred) and boiled the mixture until per- 

 fectly fluid, after which it was placed in a conical glass and al- 

 lowed to stand until a sediment had formed. Upon decanting 

 the supernatant liquid, tubercle-bacilli otherwise difficult or im- 

 possible to find were readily discovered in stained cover-glass 

 preparations made from the sediment in the bottom of the 

 vessel. In a recent article Biedert again dwells on the value of 

 this method. Although the process requires considerable time, 

 the advantage to be gained by concentrating the tubercle-ba- 

 cilli in a larger quantity of sputum into a small sediment is 

 obvious. This is also a convenient method for preserving spu- 

 tum for subsequent examinations, as the bacteria remain un- 

 changed for a considerable time. 



Processes based upon Biedert, have been proposed, such as ; 



Kaatzor (Wood^s Monographs, V, 1890, p. 97.) employed from 

 a 1 to 3 per cent solution of caustic soda or potash, which dis- 

 solved the cells, mucus, etc., but preserved the elastic fibers and 

 bacteria. Cover-glass preparations were made from the sedi- 

 ment. He also employed a dilute solution of acetic acid to 

 clear the preparations. 



Kiihne (Centralblatt f. Bakteriologie u. Farasitenkunde, VIII, 

 1890, p. 293., added an equal volume of a saturated aqueous so- 

 lution of borax to the sputum in order to overcome its viscid- 

 ity and to obtain a thin even layer on the cover-glass. This 

 mixture remained good for several weeks. Putrefaction is pre- 



