XL] BACILLUS: PATHOGENIC FORMS. 145 



in the blood of the organs, and especially of the spleen. He 

 succeeded in cultivating the bacilli artificially, by placing a 

 bit of such a spleen in a drop of aqueous humour, and 

 watching the growth of the bacilli under the microscope. 

 In this manner he ascertained that the rods multiply by 

 division, and that they grow into long, homogeneous-looking, 

 straight or twisted filaments in which after some time, and 

 with free access of air, bright oval spores make their appear- 

 ance, while the filaments become homogeneous and swollen. 



/ ( 

 \ 



FIG. 78. HEART'S BLOOD OF A MOUSE DEAD OF ANTHRAX. 



1. Blood-discs. 



2. White blood-corpuscle. 



3. Bacilli anihrac.s. 

 Magnifying power 700. (Fresh specimen.) 



These spores become free, and when artificially cultivated or 

 injected into a rodent animal, germinate into the character- 

 istic bacilli ; these elongate and divide, and in artificial 

 cultures again grow into the long leptothrix filaments, which 

 again form spores. Koch ! saw in preparations of aqueous 

 humour kept at 35 C. in the incubator the spores germin- 

 ating after three to four hours. The single bacilli as they 

 present themselves in the blood measure between 0*005 an d 



1 Beitr. z. Biol. d. fflanzen, vol. ii. part ii. p. 288. 



L 



