54 



BACTEKIOLOGY. 



or it may be across the middle, in which case it is desig- 

 nated as equatorial. 



2. Polar germination. — The elongated spore opens at 

 one pole and the young cell thus passes out. In this case 

 the long axis of the young cell is parallel to the long axis 

 of the spore. The anthrax spore germinates in this way 

 (Pig. 14 &). 



3. Equatorial germination. — The lengthened spore opens 

 as the result of a split across the iniddle. In some forms, 

 as the B. megaterium, the spore-wall is divided into two, 

 and the two halves are pushed asunder by the young 

 cell. In the case of the B. subtilis the cleft is incomplete. 

 In such instances the young rod leaves the spore -wall either 

 by doubling up, forming a horse shoe as it were, or it rotates 

 and passes out at right angles to the long axis of the spore 

 (Fig. 14 c, d, e). 



(W) (M) (SS) GZD) 



a c 



C [^ \mm Im^^ 



J s 



01 [> 



d 



Fig. 14. Spore germination, a. — Direct conversion ef a spore into a bacillus without 

 the shedding of a spore-wall (B. leptosporus); i —Polar germination of B. anthracis; c— 

 Equatorial germination of B. subtilis; ii. — Same of B. megaterium; e. — Same with "horse- 

 shoe" presentation. 



In addition to a suitable soil, the germination of a spore 

 is markedly influenced by the temperature. The process 

 will take place slowly at a low temperature, and more rap- 

 idly at or near the temperature of the body. In the latter 

 case it may require from 3 to 5 hours. When a mass of 

 spores is present, the germination of some may be greatly 

 delayed as compared with others. This fact must be taken 

 into account in the sterilization of culture media. 



Structure of the spore. — A rather dense, impenetrable 

 envelope or membrane invests the contents of the spore. 



