BACILLUS SUBTILIS. 395 



they soon disappear entirely, so that the spores become 

 free, as a rule, during the course of one day. The 

 spores are 1'2 /*. in length, and "6 /*. in breadth ; when 

 they are looked at from above they appear round. 

 Around their dark centre there is a distinct light area, 

 which is also seen when several spores are lying together. 

 The sprouting of the spores ofteA does not begin at the Sprouting cf 



... the spores. 



ordinary temper- 

 ature of the room 

 till after 12 hours; 

 it occurs most 

 quickly when the 

 spores are boiled 

 for five minutes 

 in the nutrietft 

 solution, the 

 material being 

 then allowed to 

 cool slowly; under 

 these circum- 

 stances sprouting 

 occurs even after 

 two to three hours. 

 When this takes 



place the spores 



lose their dark Fig. llS.-Bacillus^ubtilis (after Prazmowski) 



appearance, the A, colonies of bacillus subtilis. 



i . B spore formation 



clear area disap- a? ^ n a pseudo-thread, 



pears at the same , *> *? individual rods. 



. C, germination ot the spores, 



time, and a a A, successive stages. 



lighter zone appears in the middle of the spore. This 

 zone becomes larger, and then on one side a distinct pro- 

 jection is formed, at the apex of which the spore membrane 

 is ultimately ruptured in order to permit the sprouting 

 portion to pass out. The latter elongates and forms a 

 rod, but for a time the end still remains sticking in the 

 opening in the empty spore membrane as if a bladder 

 were attached to it. The spore membrane can often be 

 distinctly seen, even after repeated fission of the rods, 

 and it accompanies the moving bacilli in their wanderings. 



