182 LABORATORY METHODS OP 



by Ebert and Koch, in 1880, and was first secured in 

 pure culture from the spleen and affected lymphatic 

 glands by Gaffky, in 1884. McFarland. 



The organism is a short, small bacterium, I to 20 

 .microns in length and .5 to .8 microns in thickness. 



The ends are rounded and sometimes they unite in 

 chains, especially in the potato growth. 



The organisms are actively motile, the motility be- 

 ing due to the presence of a long flagellum. They 

 stain very well by Loffler's method, and they are used 

 to demonstrate the presence of flagella in the study of 

 bacteria in the laboratory. The organisms stain well 

 with the ordinary stains. They lose their stain with 

 Gram's stain. 



The bacillus has no spore; the dark spot seen at 

 the end of the germ is a chromatic granule. 



The bacterium is both a parasite and a saprophyte. 

 The bacterium is sometimes present in green vegeta- 

 bles which have been sprinkled with water contami- 

 nated with the organisms. This brings to mind a few 

 years ago when the city ordered that certain springs be 

 closed on account of the prevalence of the bacillus ty- 

 phosus, and at the same time prevented the marketmen 

 from sprinkling their vegetables with water from the 

 brooks on their way to town. Their reason for such 

 action is evident when we know that the organisms 



