28 BACTERIA, GENERAL CONSIDERATIONS, MORPHOLOGY 



FIG. 7 



Involution forms from bacilli. (From 

 Fliigge.) 



FIG. 8 



instance, form true branches. The 

 tubercle bacillus, the glanders bacillus, 

 and the diphtheria bacillus belong to 

 that type of bacteria which form occa- 

 sionally true branches commonly found 

 among higher microorganisms of a 

 vegetable type, namely, the moulds. 

 Bacteria which in this respect deviate 

 from the normal or average type are 

 called pleomorphous bacteria. Other 

 bacteria, as, for instance, the Bacillus 

 proteus vulgaris, may form pseudo- 

 branches, that is, false branches due 

 merely to an arrangement which resem- 

 bles the preceding type. Such pseudo- 



Fio. 9 



Glanders bacillus. (Wherry.) 

 FIG. 10 



Bacillus of bubonic plague. (Herzog.) 

 FIG. 11 



Bacillus of bubonic plague. (Herzog.) Bacillus of bubonic plague. (Herzog.) 



Figs. 8 to 11 illustrate various types of involution forms. 



