82 ANTHRAX 



food. It is inactive and is only potentially alive. When conditions 

 become favorable, the spores develop into the vegetative form. The 

 capability of passing from one form to another is a great factor in 

 protecting the bacillus against destructive agencies. Each bacillus 

 produces only one spore. There is, therefore, no multiplication in the 

 exercise of this function. The purpose seems to be solely to protect 

 the life of the individual. When times are good with plenty of air 

 and an abundance of suitable food, life seems to proceed merrily and 

 the organism multiplies abundantly. When times are hard, with inade- 

 quate air or food, the bacillus drops into the resting stage in which it 

 has no needs and awaits a change for the better. When anthrax 

 spores are brought under favorable conditions each spore develops into 

 a rod which for a while carries on one end the waste remnant of the 

 spore. Vegetative life with multiplication by fission begins anew. 



There are some strains of the bacillus which apparently are not 

 able to pass into the resting stage under any conditions. These are 

 known as asporogenous strains. According to Eisenberg, anthrax 

 bacilli are of two varieties or races, of different "biological dignity," 

 one sporogenous and the other asporogenous, and each breeds true 

 through all generations. Roux converts the sporogenous into the 

 asporogenous variety by the following method : 



Bacilli grow with the formation of spores in bouillon to which 

 from two to six parts per ten thousand of phenol has been added. 

 When the phenol has been increased to twenty parts per ten thousand 

 there is no growth. Between these limits the bacilli grow without 

 spore formation. Bacilli kept in these intermediate solutions for from 

 eight to ten days permanently lose even in following generations the 

 ability to produce spores. 



The resistance of the anthrax bacillus depends on the presence or 

 absence of spores. The latter are among the most stabile and resistant 

 forms of pathogenic bacteria. They are more easily killed than the 

 spores of certain nonpathogenic organisms, such as the potato 

 bacillus. Anthrax spores on silk threads supply standards for testing 

 the relative efficiency of disinfectants. Spores in cultures eighteen 

 years old have been found not only viable but capable of developing 

 into virulent vegetative organisms. Bouillon cultures of the vegetative 

 form are sterilized by heat at 80 C. (176 F.) for one minute, while 



