350 A MANUAL OF BACTERIOLOGY 



three, inky-blue dots. This is a valuable confirmatory stain for 

 the diphtheria bacillus. Cocci and streptothrix forms frequently 

 show similar inky dots, and this appearance must not be mis- 

 taken for diphtheria bacilli. Tanner treats with Gram's iodine 

 solution for half a minute after the blue. The staining solutions 

 usually keep well. 



Pugh's stain is also a very good one. It is a mixture containing 

 1 grm. of toluidine blue dissolved in 20 c.c. of absolute alcohol 

 and added to 1,000 c.c. of distilled water and 20 c.c. of glacial 

 acetic acid. The mixture is applied for two minutes. The proto- 

 plasm of the bacilli is stained a pale blue and the polar bodies are 

 deeply stained and stand out in marked contrast ; by artificial 

 light they appear a reddish purple. 



In the majority of cases, after a little experience, the Klebs- 

 Loffler bacillus will be readily recognised if present. Occasionally, 

 however, bacilli may be present which resemble the Klebs-L6 filer 

 very closely, and of which it is difficult to be certain. In such a 

 case the following points should be noted in attempting to arrive 

 at a decision : 



1. The character of the growth on the medium. 



2. The depth of staining with Lofner's blue, and the presence 

 or absence of segmentation or polar staining : the Klebs-Loffler 

 bacillus stains somewhat deeply, while the bacilli resembling it 

 usually stain but feebly. 



3. The presence or absence of involution, forms, clubbing, 

 etc. 



4. The presence or absence of thread forms : the Klebs-Loffler 

 bacillus does not form threads. 1 



5. The presence or absence of spores : the Klebs-Loffler bacillus 

 does not form spores. 



6. Motility in a hanging drop : the Klebs-Loffler bacillus is 

 non-motile. 



7. Gram's method of staining : the Klebs-Loffler bacillus 

 stains well. 



8. The grouping of the organism : the parallel grouping of the 

 Klebs-Loffler bacillus is somewhat characteristic. The bacilli 



1 Klein and others have described thread and branched forms in cultures 

 of the Klebs-Loffler bacillus in certain circumstances, but these are not 

 likely to be observed in young throat cultures. 



