36 BACTERIOLOGY. 



drum-stick, or a lozenge, depending upon whether the 

 location of the spore is to be at the pole or in the centre 

 of the cell. 



In addition to the property of spore-forraation there is 

 another striking difference between the members of the 

 rod-shaped organisms, namely, the property of motility 

 which many of them are seen to possess. This power of 

 motion is due to the possession by the motile bacilli 

 of very delicate, hair-like appendages or flagellse, by the 

 lashing motions of which the rods possessiug them are 

 propelled through the fluid. In some cases the flagella? 

 come oif from but one end of a bacillus, either singly or 

 in a bunch ; again, they may be seen at both poles, and 

 in some cases, especially with the bacillus of typhoid 

 fever, they are given off from -the whole surface of the 

 rod. 



For a long time the motility of certain of the bacteria 

 was supposed to be due to the possession of some such 

 form of locomotive apparatus because similar appendages 

 had been seen in certain of the large motile spirilla? found 

 in stagnant water, but it was not until very recently 

 that the accuracy of this suspicion was actually demon- 

 strated. By a special method of staining, Loffler has 

 been able, in a number of cases, to render visible these 

 hair-like appendages. His method cousists in the em- 

 ployment of a mordant, by the aid of which the flagellse 

 are caused to retain the staining, and thus become 

 visible. Ldffler's method of staining will be found in 

 the chapter devoted to this part of the technique. 



