122 Lectures on Bacteria. [ xn. 



XII. 

 Anthrax and Fowl-cholera. 



LEPTOTHRIX buccalis, as the exciting cause of caries in the 

 teeth, carries us on to those parasites in warm-blooded animals 

 which produce disease. 



The best way to obtain a clear idea of these organisms, their 

 manner of life, and their effects will be to examine first of all 

 some comparatively well-known examples. 



Let us take first the disease known as anthrax, charbon, sang 

 de rate and its exciting cause, Bacillus Anthracis (56). 



Bacillus Anthracis has already been repeatedly brought be- 

 fore our notice. Its description will therefore only be briefly 

 recapitulated here, and its figure reproduced (Figs. 17, 18). It 

 consists of cylindrical cells about 1-1-5 /u ^ n thickness, and 3-4 

 times that length. In the blood of animals these cells are usually 

 connected together into long straight rods (Fig. 17, c), which 

 appear homogeneous till they are carefully examined, that is, do 

 not distinctly show segmentation into individual members. When 

 grown in a dead substratum the rods develope into very long 

 filaments, which appear sharply bent in several places, and form 

 curvatures and loops ; they also separate at the points of flexure 

 into rod-shaped pieces, and are usually collected in large numbers 

 into bundles or sheaves and twisted round one another (Fig. 1 7, a). 

 The rods and filaments are without the power of locomotion, 

 except in special cases, which will be noticed below. The 

 formation and germination of the spores take place in the 

 manner described in Lecture III in the case of the endosporous 

 Bacilli; in germination the spores merely grow in length 

 (Fig. 1 7, b} without throwing off any distinct spore-membrane, 

 and the young germ-rod often exhibits a slow oscillating move- 

 ment. The ripe spore is broadly ellipsoidal, as broad as its 

 mother-cell which retains its cylindrical shape but much shorter, 

 and lies very nearly in the middle of the mother-cell till it is 

 set at liberty by the swelling of the membrane. 



