iS4 PRACTICAL BACTEKIOLOGY. 



tlie aniliae dyes. la order to stain its flagella it is 

 best to use part of a culture oa agar-agar whicli has 

 been kept at a temperature of 37°, and whicli is ten 

 days old. In addition to the mordant described on 

 p. 138, it is well to use five drops of the sulphuric 

 acid, which is neutralized by the one per cent, solu- 

 tion of caustic soda. 



The Bacillus pyocyaneus consists of very small 

 slender rodlets, occurring either alone, or united 

 together in short threads, which are composed of 

 only a feW- cells. Their length is always greater 

 than their breadth, and they may easily be distin- 

 guished from micrococci by the fact that their longer 

 cell-walls, for some short distance at any rate, are 

 parallel. On an average they are a little more than 

 ToVo mm. long, and to'oo to ^g^ mm. broad. They 

 are exceedingly motile and active, and, as may be 

 demonstrated if they are treated according to Loffler's 

 method for staining flagella, to possess one, or more 

 rarely two flagella at one or both poles; these flagella 

 are rather long and thin. 



Many cells are swollen somewhat in the middle, 

 and at these points show more marked refractive 

 powers ; it has not yet been worked out, whether 

 this appearance is due to the formation of spores, or 

 to the degeneration of the cells, the extreme minute- 

 ness of the organisms rendering observation of them 

 by no means simple. 



