184 Methods of Observing Micro-organisms 



Gram-negative. Gram -positive. 



Bacillus anthracis symptomatici ; Bacillus aerogenes capsulatus; 

 Bacillus coli (whole group); Bacillus anthracis; 



Bacillus ducreyi; Bacillus botulinus; 



Bacillus dysenteriae; Bacillus diphtherias; 



Bacillus icteroides; Bacillus subtilis (whole group); 



Bacillus influenzae; Bacillus tetani; 



Bacillus mallei; Bacillus tuberculosis (whole acid- 



Bacillus cedematis maligni; fast group); 



Bacillus pestis bubonica; Diplococcus pneumonias; 



Bacillus pneumonias (Friedlander) ; Micrococcus tetragenus; 

 Bacillus proteus vulgaris; Staphylococcus pyogenes albus; 



Bacillus pyocyaneus; Staphylococcus pyogenes aureus; 



Bacillus rhinoscleromatis; Streptococcus pyogenes. 



Bacillus suipestifer; 

 Bacillus suisepticus; 

 Bacillus typhosus (whole group) ; 

 Diplococcus intracellularis meningitidis; 

 M icrococcus cat arrh al is ; 

 Micrococcus gonorrhreae (Neisser) ; 

 Micrococcus melitensis; 

 Spirillum cholerae asiaticae; 

 Spirillum cholerae gallinarum; 

 Spirillum cholerae nostras; 

 Spirillum metschnikovi; 

 Spirillum tyrogenum; 

 Spirochaete duttoni; 

 Spirochaete obermeieri; 

 Spirochaete refringens; 

 Treponema pallidum; 

 Treponema pertenue. 



No matter how carefully the method is performed, an 

 unsightly precipitate is sometimes deposited upon the 

 tissue, obscuring both its cells and contained bacteria. 

 Muir and Ritchie obviate this (i) by making the staining 

 solution with i : 20 aqueous solution of carbolic acid instead 

 of the saturated anilin solution, and (2) by clearing the 

 tissue with oil of cloves after dehydration with alcohol. 

 The oil of cloves, however, is itself a powerful decolorant 

 and must be washed out in xylol before the section is 

 mounted in Canada balsam. 



Gram's method is also employed to aid in differentiat- 

 ing similar species of bacteria in culture. A thin layer of 

 a suspension of the bacteria to be examined is spread upon 

 a slide or cover-glass, dried, and fixed; then flooded with 

 the anilin-oil gentian violet or other staining solution. 

 The solution is kept warm by holding the glass flooded 

 with the stain over a small flame. The process of staining 

 is continued from two to five minutes. If the heating 

 causes the stain to evaporate, more of it must be added 

 so that it does not dry and incrust the glass. 



