BACTERIA 



657 



B. stibtilis, which is the Bacillus common to decomposing hay 

 infusion, has a life-history extremely similar to B. anthracis. It 

 spores in precisely the same manner. The outer wall of the spore 

 Is comparatively thick, and the protoplasm elongates in the direction 

 of the longer axis of the spore and of the mother-cell with which 

 this coincided. B, fig. 491 , represents the development of B. subtilis : 

 1 shows fragment of filaments with ripe spores ; at 2 the spore is 

 beginning to germinate ; 3, the young rod is projecting from the wall 

 of the spore ; 4 represents germ-rods curved in a horseshoe shape 

 and with the extremities connected, one of them having one extremity 

 subsequently released ; 5, germ-tubes with the two extremities 



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-pores (Tieghem and Cienkovvski). 



remaining connected and already greatly increased in size. The whole 

 represents a magnification of 600 diameters. 



II. Arthrosporous forms are reproduced by the separation of 

 single members from their connection with a group, which then 

 give origin to new generations. These cells, apparently not differing 

 from the rest, become larger, with tougher walls ami more refrac- 

 tive, and while the rest of the group die they, having acquired the 

 properties of spores, can produce a new growth in any fresh 

 nourishing soil. 



A sufficiently detailed illustration of the arthrosporous Bacteria 

 may be seen in Lcuconostoc m-esenteroides (fig. 492). This micro- 

 organism occurs occasionally in beetroot juice and the molasses of 

 sugar-makers, forming large gelatinous masses resembling frog spawn. 



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