BACILLUS ANTHRACIS 25 



in short chains of two to six members. The indi- 

 vidual cells are square-ended, and stain strongly 

 with any of the basic aniline dyes, and also by 

 Gram's method. In stained specimens, owing to 

 the original rectangular shape of the bacillus and 

 the shrinkage due to the methods of preparation, 

 the organism not unfrequently appears somewhat 

 concave at the ends and sides, so that the chain of 

 cells looks like a piece of jointed bamboo. The 

 photograph shows some of the cells strongly and 

 evenly stained, while others, owing to a degenera- 

 tion or loss of their protoplasm, are irregularly or 

 not at all stained, the position of the bacillus being 

 indicated only by the faint outline of the cell enve- 

 lope. This sheath, surrounding the protoplasmic 

 contents of the cell, is occasionally very plainly 

 seen, as in the preparation represented in Fig. 16. 

 Though not always capable of being demonstrated, 

 the sheath is a constant feature of the bacillus, and 

 a development of the envelope has been regarded 

 by Metchnikoff and Sawtchenko as, probably, a 

 means by which the bacillus protects itself against 

 bactericidal substances. In the blood, unless it has 

 been shed for some time and kept under condi- 

 tions favourable for the saprophytic growth of 

 the bacillus, as occasionally happens in organs 



