BACILLUS DIPHTHERIA 563 



results. Such forms are usually straight, of smaller size than their 

 neighbors, and are more often stained with great uniformity. These 

 are spoken of by Beck 5 as the "ground type," and assumed, for insuf- 

 ficient reasons, to be the young individuals. Branched forms have been 

 described by some investigators. They are rare and probably to be 

 regarded as abnormal or involution forms due to unfavorable environ- 

 ment. 



The organisms stain with the aqueous anilin dyes. A characteristic 

 irregularity of staining which is of great aid in diagnosis is best obtained 

 with Loeffler's "alkalin methylene-blue." (For preparation see section 

 on Staining, p. 115.) Stained with this solution for five to ten minutes 

 many of the bacilli appear traversed by unstained transverse bands 

 which give them a striped or beaded appearance. The longer indi- 

 viduals often have a strong resemblance to short chains of strepto- 

 cocci. Others may appear unevenly granular. In cultures which are 

 about eighteen hours old, many of the bacilli may show deeply stained 

 oval bodies situated most frequently at the ends. These are the so- 

 called "polar" or " Babes-Ernst " bodies. 6 Special stains have been 

 devised for the demonstration of these appearances. One of these was 

 originated by Neisser, 7 who claims for it differential value in distinguish- 

 ing these organisms from pseudodiphtheria and xerosis bacilli. 



His method requires two solutions : 



1. Methylene blue (Griibler) 1 gram. 



Alcohol, 96 per cent 20 c.c. 



Glacial acetic acid 50 ' ' 



Water 950 ' ' 



2. Bismarck brown 2 grams. 



Water 1,000 c.c. 



The cover-slip preparation, after having been fixed, is stained with 

 solution No. 1 for one to three seconds. It is then washed in water and 

 immersed for from three to five seconds in solution No. 2. With this 

 stain the bodies of the bacilli appear brown, the polar granules blue. 



Our own choice of a stain is toluidin blue. A staining solution can 

 be made up as follows according to the original formula, we believe, of 



5 Beck, in Kollc und Wassermann, ii, p. 773. 



6 Babes, Zeit. f. Hyg., Bd. v, 1889. 



7 Neisser, Zeit, f. Hyg., xxiv, 1897. 



