158 APPLIED BACTERIOLOGY 



able conditions this process may continue until chains of 

 great length have been formed. When the bacilli have a 

 good supply of oxygen, and the temperature is between 

 24° or 26° C, spores are developed. In sporulation the 

 protoplasm first becomes granular, and clear spaces occur, 

 which soon take a definite oval shape and become highly 

 refractive. The substance of the bacilli will then gradually 

 break down and dissolve, leaving the spores free. When- 

 ever a free spore finds itself in a suitable medium for its 

 development, it elongates and loses its high refractivity, and 

 the protoplasm bursts through the membranous wall and 

 escapes as a bacillus. 



When spores develop in a chain of bacilli, they do so at 

 fairly regular intervals. These chains of bright spores 

 have been aptly described by various authors as resembling 

 chains of pearls. A variety, first obtained by Behring, 

 which is sporeless for many generations, is produced by 

 heating the culture above bipod-heat for some time, or by 

 cultivating several times on nutrient gelatine containing 

 O'l per cent, of phenol. 



In speaking of the organism as it occurs in blood, it was 

 stated that the ends were slightly convex ; on cultivating 

 they become slightly concave, but neither of these modifica- 

 tions is ever so great as to interfere with the characteristic 

 squareness of appearance. This concavity is regarded as 

 indicating an attenuated virulence. Involution forms are 

 often seen in old and attenuated cultures. 



Growth on Media.— On the gelatine plate small spherical 

 colonies develop in the depth, which consist of closely- 

 twisted bands of bacilli chains. When the growth reaches 

 the surface, chains of bacilli at once begin to spread out 

 over the surface in the most beautiful wavy convolutions, 

 liquefying the gelatine. This stage is usually reached in 

 two days, and is most characteristic. In the gelatine stab, 



