162 CLASSIFICATION OF THE MICRO-ORGANISMS. 



20 hours highly refracting spores with dark contours, 

 and for the most part egg-shaped, are formed from these 

 granules, and the threads present a moniliform appear- 

 ance ; the latter become gradually dissolved, and the 

 spores are liberated and sink to the bottom of the fluid. 

 In another mode of spore formation the bacilli do not 

 grow out in the form of long pseudo-threads, but become 

 broader; they thus assume spindle, elliptical, or tadpole 

 'forms, while at the same time the whole plasma becomes 

 denser, and the membrane thickened. The contents then 

 become turbid, and highly refracting largish drops are 

 differentiated and transformed into the spores (spore 

 formation in Clostridium butyricum according to Praz- 

 mowski). In other cases 2, 3, or more small spherical 

 refracting points, which represent the spores, appear in 

 the bacillus without the latter having undergone any 

 marked alteration ; or a spherical or oval spore which 

 often markedly exceeds in diameter the parent bacillus 1 

 develops at one etid of the rod. If a similar spore 

 formation occurs at both ends of the bacillus, bodies are 

 formed of a dumb-bell appearance. At times the spores 

 bulge out the contour of the bacillus in a remarkable 

 manner, so that the latter appears as if covered with 

 small swellings. 



The spores formed in this way within the cells appear 

 when isolated as spherical, generally however longish 

 egg-shaped cells of 12*5 JJL in longitudinal diameter, 

 and 0*5 1 ^ in transverse diameter. Their marked 

 refracting power is very striking ; it gives the impression 

 as if their contents consisted of a bright oil globule. At 

 the same time the refraction is not altered by boiling 

 with ether, so that the contents cannot be regarded as 

 fat, but rather as condensed protoplasm. The thickness 

 Of the wall is well-marked ; at times two layers, an exo- 

 sporium and an endosporium, can be differentiated, and 

 there is often a peculiar clear area around it, which is 

 sometimes regarded as a spherical clear mass in which 

 the cells are embedded, sometimes however only as an 

 optical appearance due to the high refracting power of 

 the spore. 



