348 W. A. HAGAN 



microscope stage and the edge of the colony carefully focussed 

 upon with the ^ mm. objective (fig. 1). 



A true anthrax colony under these conditions shows beautiful 

 festoons of parallel, closely packed filaments. The arrangement 

 has been aptly compared to a carefully combed coiffure. Very 

 seldom is the end of any filament seen at the colony margin; 

 they appear to begin and end in the depths of the colony. A 

 rather peculiar character, at first thought, is the fact that the 

 filaments, unless examined very diligently, appear to be homogene- 

 ous and do not show the divisions between the individual organ- 

 isms. I have not seen this character nearly so well marked in 

 any of my anthrax-like colonies. It is undoubtedly due to the 

 almost absolute squareness of the ends of the bacteria. In the 

 case of other organisms which have ends slightly rounded and 

 which form filaments, the individual elements are plainly shown 

 because of the reflection and refraction of light from the curved 

 surfaces of the ends of the organisms. My photomicrograph 

 does not illustrate this character well for the camera seems to 

 have detected the individual organisms much better than the 

 eye is able to do. 



The true anthrax colonies show few or no spores until after 

 twenty-four hours when grown on 1.5 per cent beef infusion agar. 

 This point aids in differentiating certain species which sporulate 

 abundantly before this time. 



The anthrax-like colonies show various characters which it 

 would not be profitable to discuss here. At least half of these 

 types prove to be motile organisms and are easily eliminated by 

 this character. The motility is observed only at the extreme 

 margin where a comparatively few organisms swim around ac- 

 tively. Many other organisms lie entirely free but with no 

 signs of movement so it is probable that the motile stage is of 

 very short duration. Certain observers have claimed that some 

 organisms of this type were not motile in the primary culture 

 but developed motility later in subcultures. This is probably 

 explained by the observation above. 



The arrangement of the filaments in none of the anthrax-like 

 organisms has been exactly like that of the true anthrax. Fre- 



