ix.] BACILLUS. 73 



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 form 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 reagents, &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 (loc. cit.) 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 anthrax-bacillus and 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 to 15 C. for one 

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

 (5-10 per cent.), strong solutions of phenyl-propionic acid and 

 phenyl-acetic acid, corrosive sublimate (1 : 300,000, Koch), 

 although the spores were kept in these fluids for twenty -four 

 hours, did not kill them. 



Pure terebene, phenol (10 per cent.), corrosive sublimate (1 

 per cent), does not kill the spores of bacillus anthracis. 



This great resistance of spores to low and high tempera- 

 tures, to acids and other substances, is due to this, that the 

 substance of each spore is enveloped in a double sheath : an 

 internal sheath probably of a fatty nature, and an external one 

 probably of cellulose ; both are very bad conductors of 

 neat. 



Owing to the fact that spores resist the action of boiling 

 water, if not prolonged for ten minutes, and that the other 

 bacteria (such as micrococcus, bacterium, and bacillus itself) 

 are killed by the temperature of boiling water if kept at this 

 temperature for a few seconds, it is possible to separate the 

 spores of bacilli from the other organisms. All one has to do 

 is to subject the fluid containing these various organisms to the 

 temperature of boiling water for a few seconds. All except 



