I04 MICRO-ORGANISMS AND DISEASE [chap. 



animals dead of the disease, does not at any time form 

 spores when kept away from the air— /.^., from a supply of 

 oxygen ; consequently in such an animal when left unopened 

 all the bacilli, after having gone on increasing in numbers 

 after death for some time, gradually degenerate and dis- 

 appear, so that sometimes after five to eight days in the case 

 of small animals like mice and guinea-pigs, living anthrax 

 bacilli are no longer to be found in the tissues, they having 

 been suppressed by putrefactive organisms. The spleen of 

 such an animal after this distance of time produces no in- 

 fection with anthrax after inoculating it in comparatively 

 large doses into a fresh guinea-pig or mouse ; whereas if a 

 trace of a droplet of the splenic blood of an animal dead 

 of anthrax is used for inoculation of a guinea-pig or mouse, 

 say within three days after death, virulent anthrax follows. 

 Or if the blood and tissues of an animal dead of virulent 

 anthrax are by some means or other thoroughly dried, such 

 blood loses all virulent power, since by thorough drying the 

 bacilli anthracis are killed. But let either the blood or the 

 nasal or other discharges of an animal dead from anthrax 

 be exposed to air for a sufificient time to allow the 

 bacilli to form spores, then neither putrefaction, nor drying, 

 nor chemical agencies such as acids and alkalies, will affect 

 the power of these spores to germinate again into bacilli and 

 to produce virulent anthrax when finding access to a suitable 

 animal body. This is actually the case when cattle and sheep 

 are sojourning on and feeding in a field, where months or 

 even years previously an animal having died from anthrax, 

 the blood and discharges of such an animal found access 

 to the surface of the soil, that is where the bacilli anthracis 

 find opportunity to multiply and to form spores. It is 

 these spores which afterwards are picked up by the animals 

 grazing in such a field. The same thing occurs in wool- 



