xvii.] SEPTIC AND PATHOGENIC 



transforming the common bacillus of 

 bacillus, into the bacillus anthracis. 



The hay bacillus and the bacillus anthi 

 morphologically under that form which Colm has namt <! 

 bacillus subtilis. 



The two are, however, not quite identical in morphological 

 respects. The hay bacillus is a minute rod or cylindrical- 

 shaped bacillus, which by elongation and division produces 

 chains and further threads just like the bacillus anthracis, but 

 in the latter (i.e. bacillus anthracis) the bacilli and their threads 

 are composed of cubical elements, as is shown in stained speci- 

 mens, and as has been mentioned in a former chapter, whereas 

 in those of the hay bacillus the elements are reds or cylinders. 

 I have seen, however, many of the short hay bacilli which 

 being constricted, i.e. in the act of division, appear as two short 

 more or less cubical elements placed end to end. It is generally 

 assumed that in hay bacillus the bacilli are always rounded at 

 their ends, whereas the bacilli anthracis are as if straight cut 

 at their ends ; but this is not universally the case, since I have 

 seen in cultures the bacilli anthracis with distinctly rounded 

 ends. But, speaking generally, the hay bacillus is a rod more 

 distinctly rounded at its ends, the bacillus anthracis of the 

 blood is not so. 



The bacillus anthracis is slightly thicker than the hay 

 bacillus. In artificial cultivations carried on in neutral broth 

 the bacillus anthracis is about twice as thick as the hay bacillus 

 growing in the same fluid, and when both are growing in 

 neutralised hay infusion the two are very conspicuously different 

 from one another, and can at a glance be distinguished from 

 one another ; the hay bacillus being about half the thick- 

 ness of the bacillus anthracis. In stained specimens, too, the 

 latter is beautifully made up of a row of cubical cells, whereas 

 the former consists of cylinders only. 



True, the bacillus anthracis is not always of the same 

 thickness, for, as I have shown, when growing in neutral 

 pork broth it is decidedly thicker than in the blood of an 

 animal dead of anthrax. And also in the blood of different 

 animals the bacillus anthracis slightly varies in thickness, for 

 in the guinea-pig's blood it is slightly thicker than in that of 

 the rabbit or sheep. 



The hay bacillus is motile, possessed of a flagellum, and 

 therefore capable of locomotion ; the bacillus anthracis is 

 not motile. I am quite aware that Cossar Ewart (Quarterly 

 Jmirnal of Microscopical Science, April 1878) states that he 

 has seen in a specimen kept artificially heated under micro- 



