68 MICRO-ORGANISMS AND DISEASE. [CHAP. 



putrefaction has set in, c.), are possessed of a flagellum at 

 one end, and are therefore endowed with the power of loco- 

 motion. Other species (e.g. anthrax-bacillus, bacillus of 

 malignant rederna) are without such power. But even in the 

 first case the power of locomotion is possessed by the bacilli 

 only when single or in short chains, not by the longer chains 

 or leptothrix. 



(c) Not all bacilli are capable of forming leptothrix -fila- 

 ments. This power is possessed in an eminent degree by 

 certain species, such as the hay-bacillus, the anthrax-bacillus, 

 the bacillus of malignant oedema, the bacillus found on the 

 surface of the mucous membrane lining the cavity of the 

 mouth and tongue (leptothrix buccalis). Other bacilli (e.g. 

 bacillus amylobacter, leprosy-bacillus, tubercle-bacillus, &c.), 

 generally do not form leptothrix. 



(d) There exists the greatest variety in reference to the 

 thickness of the bacilli ; some (e.g. bacillus amylobacter, and 

 some species occurring in ordinary putrefaction) being several 

 times as thick as others like hay-bacillus, anthrax-bacillus, &c. 



Many bacilli and bacillus-filaments (e.g. hay-bacillus, an- 

 thrax-bacillus) degenerate on growing old, the protoplasmic 

 elements becoming granular and breaking down altogether 

 into debris. This may occur to single elements within a chain 

 or leptothrix ; and then the corresponding part of the sheath 

 of the chain, owing to the subsequent disappearance of the 

 debris, becomes empty and devoid of protoplasm. Longer or 

 shorter portions of a chain or leptothrix may thus degenerate 

 and become deprived of protoplasm, the sheath only persisting. 

 These portions become at the same time thicker, the sheath 

 having swollen up. 



Another mode of degeneration consists in the elements and 

 sheath curling up, swelling up, and ultimately breaking down 

 into debris. According to Cohn, 1 bacilli do not form zoogloea 

 in the same way as micrococcus and bacterium do. With all 

 due deference to the authority of Cohn, I must hold that the 

 bacilli possessed of a flagellum are capable of forming a true 

 zooglcea. When one inoculates a fluid-nourishing medium 

 (eg. broth) with hay -bacillus or other motile bacillus of 

 common putrefaction, after keeping it for twenty-four hours in 

 the incubator one notices a uniform turbidity. After several 

 days one notices that the surface of the fluid becomes covered 

 with a whitish film ; this, as incubation goes on, thickens into 

 a thick resistent not very friable pellicle. By shaking the 

 fluid the pellicle becomes detached from the glass wall and 



1 Beitr. z. Biologie d. Pftanzen, vol. ii. 



