334 BACTERIOLOGY. 



same culture individual bacilli differ much in their 

 size and shape. The two bacilli of a pair may lie 

 with their long diameter in the same axis or at an 

 obtuse or an acute angle, or the pairs of bacilli may 

 lie side by side or irregularly across each other. The 

 bacilli possess no spores, but have in them highly 

 refractile bodies at certain stages in their life. 



The Klebs-Loffler bacilli stain readily with ordinary 

 aniline dyes, and retain fairly well their color after 

 staining by Gram's method. When Loffler's alkaline 

 solution of methylene-blue is applied cold for five min- 

 utes or warm for one minute the bacilli from blood- 

 serum cultures especially, and from other media less 

 constantly, stain in an irregular and extremely charac- 

 teristic way (see Fig. 41). Many of the bacilli do not 

 stain uniformly. In many cultures round or oval 

 bodies situated at the ends or in the central portions 

 stain much more intensely than the rest of the bacillus. 

 Sometimes these highly stained bodies are thicker than 

 the rest of the bacillus; again, they are thinner and 

 surrounded by a more slightly stained portion. The 

 bacilli seem to stain in this peculiar manner at a cer- 

 tain period of their growth, and more when grown on 

 some media than on others, so that only a portion of 

 the organisms taken from a culture at any one time 

 will show the characteristic staining. In old cultures 

 the bacilli stain poorly and not at all in a characteristic 

 way. The same round or oval bodies which take the 

 methylene-blue more intensely than the remainder of 

 the bacillus are brought out still more distinctly by the 

 Neisser stain. 



The Neisser stain is carried out by placing the cover- 

 slip smear of diphtheria or other bacilli in solution No. 



