ix.] BACILLUS. 105 



It is a rule that wherever the spores are formed they ger- 

 minate into bacilli if they have access to nourishing material ; 

 but if not, or if the nourishing material is exhausted, they 

 remain as spores. Spore-formation does not take place at 

 low temperatures. Koch found in the case of anthrax-bacillus 

 that a temperature below 12 C. prevents the formation of 

 spores. Pasteur states that in the case of anthrax-bacillus 

 spore-formation does not take place above 40 C. ; never for 

 instance at 42 or 43 C. Koch gives 43 as the upper limit ; 

 but I have found that both in the case of hay-bacillus and 

 anthrax-bacillus the bacilli lorm spores copiously even at a 

 temperature of 44 C. Moisture is an essential element 

 in the formation of spores. 



The spores represent the seeds capable of retaining life 

 and of germinating into bacilli even after what would appear 

 the most damaging influences (that is, damaging to all other 

 kinds of organisms and to the bacilli themselves), such as 

 long lapse of time, drying, heat, cold, chemical re-agents, &c. 

 Spores retain the power to germinate into bacilli after the 

 lapse of long periods, and there is no reason to assume that 

 these periods have any limit ; it makes no difference whether 

 they are kept dry or in the mother-liquid. 



The temperature of boiling water, while it kills micrococci, 

 bacteria, and bacilli themselves, does not affect the vitality of 

 the spores. Cohn (foe. tit.) found spores of hay-bacillus still 

 capable of germination even after boiling ; boiling for half an 

 hour or more killed them. Prazmowski found that the spores 

 of bacillus butyricus (amylobacter) are killed by five minutes' 

 boiling. In the case of bacillus subtilis, e.g. hay-bacillus, I 

 found that boiling for half an hour does invariably kill them, 

 but ten minutes is not to be relied on. Exposing the spores 

 of anthrax-bacillus to a temperature of o to 15 C. for one 

 hour did not kill them. Antiseptics, such as carbolic acid 



