362 



Nini'.Ri l\ AKV I'ATIIOLOCV. 



more prevalent in those portions of a countrv in which there is 

 extensi\e horse traffic, 'ihe in\asion of a pruvince or a country 

 b_\- an arm\- is iisualK- succeeded bv tlie appearance of g;landers. 



Etiology. — (danders is caused by the Bacterium mallei. This 

 orqamsm was descri1)ed ijy se\'eral different investig'ators in 

 ISS'i. It is similar in ap])earance tt> the Bacterium tuberculosis, 

 has riiunded ends, is from 2 to ■'i.o microns in length and .3 to 

 .5 micrijus in widtli. This bacterium occurs singh^ except that 

 when grown upon pijtato medium, pairs or even long filaments 

 are not rare. Like, tlie Bacterium tul^erculosis, it produces ple- 

 oniiir])liic forms when culti\-ate(l in different media or under 

 varying conditions. In old cultures it frequently becomes 

 short and is sometime coccoid in api)earance. liranching- forms 

 arc not uncommon. It does not form spores. 



The Bacterium mallei is stained l)v acpieous solutions of ana- 



199.— Bacterium Mallei, .\100n. 



line dyes that are slightly alkaline in reaction, such as Loef- 

 fler's methylene l)lue. It is so-called "Gram negative," i. e., 

 it is deci.'lorized by (iram's solution. 



Source of Infection. — Infecticjn probably occurs most fre- 

 fluently in an indirect manner, i. e., the infection is obtained 

 from some surrounding object en" thing that has been contamin- 

 ated ^\ith the infected discharges of a glandered animal 



The Bacterium mallei is strictly parasitic and the source of 

 the micro-organism is either the discharges from an infected 

 animal or the carcasses of animals that have died of 

 glanders. Fortunately this bacterium possesses little re- 



