408 BACILLI OF NO KNOWN PATHOGENIC PROPERTIES. 



Spore forma- 

 tion. 



Germination 

 of the spores. 



Cultivation. 



ends ; it elongates till it is four to six times as long 

 as broad, and then divides transversely into two halves ; 

 when acted on by alcohol or tincture of iodine the rods 

 are seen to be composed of short segments. They are 

 slightly bent; at times they form chains, which, however, 

 rarely consist of many segments. The rods are in con- 

 stant, though relatively slow, movement ; flagella have 

 not been observed. At a later period it can be seen 

 that each rod is composed of four to six isodiametric 

 cells, separated from each other by delicate transverse 

 divisions ; a small, round, highly refracting body soon 

 appears in the cell, this body increasing in size while 

 the surrounding protoplasm gradually disappears ; 



after a few hours it be- 

 { comes converted into a 

 longish cylindrical spore. 

 The latter is very highly 

 refracting, of a bluish ap- 

 pearance ; the membrane 

 of the mother cell gradu- 

 ally disappears ; and the 

 spore becomes free. 

 During the process of 

 formation of the spores 

 the movement of the 



Fig. 115. Bacillus megaterium. (After rods becomes slower, but 



de Bary.) ^ QGQ not en tirely cease. 



I', short roax m m ' When the spore germi- 



^, their appearance after the action of na t eg its dark outline 

 iodine solution. 



e ~f, spore formation. and its highly refracting 



character disappear, and 



it gradually increases in size till it has attained the normal 

 breadth of the rod. When this has occurred a delicate 

 membrane, which is torn transversely or obliquely, is 

 suddenly separated from the surface, and the rod 

 passes out of this membrane. The bacilli grow at 

 20 C. in solutions of grape sugar and meat extract, or 

 in meat extract alone with or without gelatine. The 

 gelatine is liquefied as the result of the growth of the 

 bacilli. 



