THIRD TYPE OF SPORE GERMINATION 53 



effected by the spore membrane, the tension of which is gradually increased to 

 such an extent, through the expansion of the spore contents, that it finally 

 squeezes out the mature spore. The capsule then shrinks at once to its original 

 size, and gradually disappears from view by swelling up and dissolving in the 

 surrounding liquid. If the spore has originated from any species of motile 

 bacteria, the liberated rod begins to rove directly one of its extremities is free. 



It not unfrequently happens that the empty spore capsule is not completely 

 detached from the germ, but rests as a well-defined cap on the rearward 

 pole for some time, until finally it disappears. In a few species the persistence 

 of this membrane is very considerable, whilst the force of contraction is small 

 and insufficient to expel the matured rod. An example of this is afforded by 

 the Bacillus sessilis, discovered by L. KLEIN (I. and II.), which as its distinctive 

 name implies remains embedded in the spore membrane. This captivity, 



A 



2 



30 



SO 



lOVhrM. 



B, 



?0 



& 



7/K 



1& 



,'& 



12 U. 



s 



61'. 



n: 



3V-1E** 



> V 



AWe. 10 to 12 Uhr M. (U.) = 10 A.M. to 12 noon ; i to 7 U. = i to 7 P.M. 



FIG. 23. Germination of spores of Bacillus sessilis. 



Progressive observation of the germination of five cndospores (1-5) under the 

 microscope at 3O-35 C. Hanging-drop culture in meat-extract solution. The time 

 of the observation (ironi 10 A.M. to 7 P.M.) is given under the illustrations of the 

 separate stages of development (A-K) of the germination. Spore 3 had not 

 germinated even at 7 P.M. (After L. Klein.) Magn. about 1000. 



nevertheless, in nowise retards its nutrition and reproduction, since by fission it 

 forms new rods, which it protrudes through the polar openings at both 

 extremities in the muff-shaped capsule, the said rods quickly forming spores in 

 turn. An illustration is given in Fig. 23. 



58. Third Type. 



In Bacillus subtilis (Fig. 24), Bacillus megatherium (Fig. 25), and ft few other 

 specie.", the spore membrane does not burst at the poles, but along a line coincid- 

 ing with the equator of the spore. This line, however, extends only part of the 

 way, not right round the spore, so that the two halves of the membrane still 

 remain attached together at one point. The rod then makes its exit by bending 

 somewhat at the centre, and, by turning one of its extremities, pushes it out of 

 the capsule, one half of which often remains on the other pole for some time like 

 a cap, the other half hanging down empty. Sometimes the germ cannot liberate 

 even one end from the capsule, both poles remaining wedged between the two 

 halves of the membrane (these acting like a pair of tongs), and the central 

 portion alone projecting. This position, however, does not prevent reproduction, 



