FORMATION AND GERMINATION OF SPORES. 131 



In the end, however, they all somehow or other get 

 rid of their spore covering, which remains like an 

 empty egg shell. If the conditions are favourable for 

 ■growth, the rodlets, when germination is complete or 

 with the spore membrane still covering one endj pass 

 through a motile stage, during which, nevertheless, 

 they divide, and gradually grow whilst becoming less 

 active into long threads, in which again, when nour- 

 ishment becomes scarce, spores are formed. 



The formation of spores and their germination do 

 not always take place in precisely the same manner ; 

 a great many variations occur, which are very useful 

 in differentiating otherwise similar species ; for ex- 

 ample, the anthrax bacillus, which is very like the hay 

 bacillus, breaks through its spore membrane at one of 

 the poles and not at the side. Again, the new rodlet 

 of the hay bacillus appears to emerge diagonally, 

 whilst that of the anthrax bacillus comes out in a 

 parallel direction. Eeally, however, this is also the 

 case with the hay bacillus, the only difference being 

 that the breaking down of the membrane occurs 

 at the side and not at one pole ; thus, according to 

 their mode of germination, bacteria may be divided 

 into two groups — those in which the spore membrane 

 breaks down at the side, and those in which it breaks 

 down at the pole. 



A still greater number of variations are to be ob- 

 served in the way in which the spores are formed in 



