354 



Anthrax 



ence of oxygen. When oxygen is withheld spore-formation does 

 not occur. In the bodies of experiment animals spore-formation 

 is unusual and its occurrence signifies the local presence of abundant 

 oxygen. On account of this peculiarity of the organism, the dead 

 body of an animal is less dangerous as a source of infection than the 

 discharges from living animals. As, however, the wool, hair and 

 hides of infected animals are always soiled by the discharges, these 

 are a menace to all that handle them and ought not be used. Each 

 spore has a distinct oval shape, is transparent, situated at the center 

 of the bacillus in which it occurs. It does not alter the contour of 

 the bacillus. When a spore is placed under conditions favorable 

 to its development, it increases in length and ruptures at the end. 



Fig. 129.— Bacillus anthracis, stained to show the spores. X 1000 (Frankel 



and Pfeiffer). 



from which the new bacillus escapes. The spores of the anthrax 

 bacillus, being large and readily obtainable, form excellent subjects ' 

 for the study of spore-formation and germination, for the study of 

 the action of germicides and antiseptics, and for staining. 



Motility. — The bacilli are not motile and have no flagella. 



Staining. — They stain well with ordinary solutions of the anilin 

 dyes, and can be beautifully demonstrated in the tissues by Gram's 

 method and by Weigert's modification of it. Picrocarmin, followed 

 by Gram's stain, gives a beautiful, clear picture. The spores can 

 be stained by any of the special methods (q.v.). 



Isolation. — The bacillus of anthrax is one of the easiest organisms 

 to secure in pure culture from the tissues and excreta of diseased 

 animals. Its luxurious vegetation, the typical appearance of its 

 colonies, and its infectivity for the laboratory animals combine to 

 make possible its isolation either by direct cultivation from the tis- 



