MORPHOLOGY OF BACTERIA 



21 



From the relation of cells to stains, the conclusion has been 

 drawn that the substance of the bacterial cell is essentially 

 nuclear in character. 



Inclusions of various kinds are sometimes to be observed 

 in the bacteria. These bodies, termed met achromatic 

 f/rtumh's, may read to the stains in such a way as to dif- 

 ferentiate them from the rest of the cell contents. Granules 

 of <rlyeoren and of sulphur are found in some species, as are 

 also droplets of oil. 



The outer layer of the cell wall is often of a gelatinous 

 nature and more or 

 less thickened, form- 

 ing what is known as 

 the ctii)sulr. It is 

 probalde thai the 

 presence of some of 

 the capsnlated bac- 

 teria causes the solu- 

 tions in which they 

 are growing to be- 

 come ropy or slimy 

 as is the case with 

 ropy bread and slimy 

 milk. Some bacteria 

 are embedded in a 

 mass of gelatinous 

 material secreted by the cells, in which case the mass of or- 

 ganisms is termed a /ooglcea. The mass may be so firm as 

 to have a leathery nature. 



Motility. Many species of bacteria have the power of in- 

 dependent motion when they are in a suitable liquid. The 

 organs of locomotion are delicate whiplike appendages var- 

 iously distributed on the cell. The term flagella (singular 

 fhii/clhun) is applied to them. A monotrichous cell is pro- 



Fig. 13. Capsules 



Each cell is surrounded by a gelatinous layer, 

 which appears as a clear space in the photo 

 graph After Orla-Jensen. 



