144 SCHIZOMYCETES 



appears to be stored actually within the bodies of the 

 bacteria. The chromogenic bacteria are therefore 

 classified, in accordance with the final destination of 

 the colouring matter they elaborate, into 



Chromoparous Bacteria: in which the pigment is 

 diffused out upon and into the surrounding medium. 



Chromophorous Bacteria: in which the pigment is 

 stored in the cell protoplasm of the organism. 



Parachromophorous Bacteria: in which the pigment 

 is stored in the cell wall of the organism. 



Different species of chromogenic bacteria differ in 

 their requirements as to environment, for the produc- 

 tion of their characteristic pigments; e. g., some need 

 oxygen, light, or high temperature; others again favor 

 the converse of these conditions. 



Light Production. Some bacteria, and usually those 

 originally derived from water, whether fresh or salt, 

 exhibit marked phosphorescence when cultivated under 

 suitable conditions. These are classed as ' ' photogenic. ' ' 



Enzyme Production. Many bacteria produce soluble 

 ferments or enzymes during the course of their growth, 

 as evidenced by the liquefaction of gelatine, the clot- 

 ting of milk, etc. These ferments may belong to either 

 of the following well-recognised classes: proteolytic, 

 diastatic, invertin, rennet. 



Toxin Production. A large number, especially of 

 the pathogenic bacteria, elaborate or secrete poisonous 

 substances concerning which but little exact knowledge 

 is available, although many would appear to be en- 

 zymic in their action. 



These toxins are usually differentiated into 



Extracellular (or Soluble) Toxins: those which are 

 diffused into, and held in solution by, the surrounding 

 medium. 



Intracellular (or Inseparate) Toxins : those which are 

 so closely bound up with the cell protoplasm of the 

 bacteria elaborating them that up to the present time 



