STRUCTURE OF BACTERIA 9 



logical and structural differentiation and physiological 

 complexity and are by no means primitive forms. 



The size of the bacteria is variable, but they are all 

 microscopic, measuring 0-3/x to 30-40^ in diameter or 

 in length. 1 Their shape likewise is very different in the 

 different species ; some are spherical, others ovoid, others 



Relation of Bacteria to Lower Plants 



Thallophyta (lower plants without fibro-vascular bundles, and with 

 no distinction between root and stem) 



Forms with chlorophyll Forms without chlorophyll 



(Algae, desmids, etc.) | 



Multicellular. Spores in Unicellular. Spores frequently 



differentiated cells or spore- absent. Spore-bearing cells not, 



bearing organs. Generally or but slightly, differentiated. 



a sexual method of reproduction Sexual reproduction usually absent 



I I 



The true Fungi (Eumycetes) 



including moulds (Hypho- Reproduction Reproduction 



mycetes) by fission by budding 



I I 



The Schizomycetes The Saccharomycetes 

 or Bacteria or Yeasts 



rod-shaped or filamentous, while in some the rod or fila- 

 ment is twisted into a spiral. The end of the cell is 

 occasionally almost rectangular, but is usually more or 

 less rounded ; it is probably never pointed except in 

 the Spirochaeta?, if these be true Bacteria (see p. 18). 

 The bacterial cell consists of a cell -membrane enclosing 

 the transparent, more or less structureless living matter 

 or protoplasm, the cell-plasma or cytoplasm. Biitschli 

 has described the bacterial plasma as having a reticular 

 structure, but in the young cell this is probably either 

 an artifact or a " false image " due to faulty illumination ; 

 the most that can be seen is a fine granulation. The 



1 p. = micron = 0-001 mm. 



