210 MICRO-ORGANISMS AND DISEASE. [CHAP. 



threads are composed of cubical elements, as is shown in 

 stained specimens, and as has been mentioned in a former 

 chapter, whereas in those of the hay bacillus the elements 

 are rods 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 thickness 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 



