204 TEXT-BOOK OF BACTERIOLOGY. 



anthrax bacillus, reaches its fullest development only in the living 

 body and not in our cultures) may have something to do with it, or 

 it may be that the hypothetical protoplasmic body contracts in this 

 peculiar manner under the influence of the alcoholic staining solu- 

 tions. It must be noted that all staining matters are not equally 

 inclined to produce this " bamboo form." Bismarck-brown and 

 methyl-blue do it best; stronger agents are apt to bl^ck up the in- 

 terstices and efface the characteristic appearance. 



It makes a difference which process of staining is emploj'^ed. If 

 we use Gram's method, for example, which is of easy application 

 for the anthrax bacilli, we see nothing of the things just described. 

 From contact with the iodine in iodide of potassium solution the 

 rods frequently even cease to look homogeneous, they become gran- 

 ulated, seem to be composed of separ te grains, and altogether lose 

 their normal appearance. 



The peculiar form of the ends of the cells which appears under 

 certain definite conditions is without doubt a characteristic mark 

 of the anthrax bacillus. It may be distinguished with certainty 

 from other bacilli by this same peculiarity, and is, therefore, in con- 

 trast to the great majority of other micro-organisms, distinguisha- 

 ble by its morphological qualities, its outward form, and by micro- 

 scopical examination alone. 



In the case of fruit-beai-ing cells, the spore remains unaffected 

 by the usual staining process. The spore double-staining is, how- 

 ever, possible, although the spores of the anthrax bacillus take car- 

 bolized fuchsin much less readily than those of some species already 

 considered ; for instance, the hay bacillus or the Bacillus megaterium. 



If we inoculate nutrient gelatin with anthrax germs and pour it 

 out upon glass plates, the colonies develop in a few days. They 

 appear at first to the naked eye as small white points, which in- 

 crease in size at a moderate speed, reach the surface, and there 

 begin to decompose the food medium. They then lie as white pel- 

 licles with jagged edges in the liquefied portion. 



Under the microscope we see in the body of the gelatin finelj^- 

 granulated, green, shining, roundish or egg-shaped accumulations, 

 whose color passes gradually more and more into brown. 



The larger surface colonies offer a very peculiar appearance. 

 The centre is slightlj' depressed, of somewhat granulated structure 

 (as far as can be judged through the thickness of the layer), and of 

 a yellowish color. The edge is surrounded by a close tangle of fibres, 

 which wind about like whip-lashes or twist round each other like 

 the snakes on the head of the Medusa. 



In watching the growth of the anthrax bacilli in a hanging drop 



