THE SPORE-BEARING RODS 353 



sometimes termed malignant carbuncle, hide-handler's dis- 

 ease and woolsorter's disease. The anthrax appears most 

 commonly in sheep, swine and cattle and somewhat more 

 rarely in horses and in man. The bacillus of anthrax is 

 of importance from a historical point of view as it was 

 the first of the pathogenic bacteria to be accurately de- 

 scribed. Pollender in 1855 stated that he had observed tiny 

 rods in the blood of animals sick with the disease anthrax 

 in 1849. In a publication in 1876, Koch completed the 

 demonstration of the cause and relationship of this organ- 

 ism to the disease. This is of importance because it is the 

 first record of the cultivation in the laboratory of an organ- 

 ism capable of causing disease and of the successful produc- 

 tion of disease by the use of pure cultures. It is of interest 

 further because Pasteur with it made the first successful 

 application of the principle of vaccination by means of 

 attenuated or weakened cultures of bacteria. 



Distribution. Bacillus anthracis is a strict parasite, 

 that is, it does not grow widely distributed in nature. There 

 are records of the occurrence of anthrax from the earliest 

 times. Outbreaks have been noted throughout Europe and 

 both Americas. In the United States there are still a few 

 localities where the disease is enzootic. 



Morphology. The bacillus of anthrax is a straight rod, 

 occurring in chains, the individual cells usually showing 

 truncate ends. The bacteria are usually 1-1.25 X 4.5-10/z. 

 When examined in tissues or blood the chains usually are 

 short, when grown in culture media the chains are long. The 

 organism is nonmotile. Capsules are present in body tissues 

 and in blood but are not readily demonstrated in culture 

 media. Spores are produced when the organism grows in 

 the presence of sufficient oxygen, but are not commonly 

 found in the blood or tissues of animals with the disease. 

 Each cell produces a single spore, oval or spherical in shape, 

 which is located in the center of the cell and is of almost 



