Kingdom My c hot a [ 19 



of endospores; metabolic products; and the peculiar character called Gram reaction. 

 The method of staining invented by Gram, 1884, consists of staining successively 

 with gentian violet and iodine. It gives an intense blue-black color. From some bac- 

 teria, this color is washed out by alcohol; others retain it; the former are said to be 

 Gram negative, the latter Gram positive. In practice one applies successively gentian 

 violet, iodine, alcohol, and safranine, the last being a red dye whose function is to 

 make the Gram negative bacteria visible. The substance stained by gentian violet 

 plus iodine is believed to be lipoid, such as occurs in all cells. The Gram positive 

 quality is believed to consist in a relatively low isoelectric point, a capacity, that is, 

 to combine with anions in a relatively acid medium. This quality lies in the ectoplasm 

 of the cells and disappears in aging cultures. 



The classification given in Bergey's Manual (1923, 1925, 1930, 1934, 1939, 1948) 

 is accepted (at least among Americans) as standard. The following system of thirteen 

 families is a moderate rearrangement of the Bergeyan system, with certain ideas or 

 names from Enderlein (1917, 1925), Buchanan ( 1925), Pribram (1929) and Stanier 

 andvanNiel (1941). 



1. Gram positive, with exceptions many of 

 which are intracellular parasites; atrichous or 

 peritrichous. 



2. Spheres dividing in more planes than 

 one. 



3. Gram positive Family 1. Micrococcacea. 



3. Gram negative; intracellular patho- 

 gens in animals Family 2. Neisseriacea. 



2. Rods, or spheres dividing in one plane. 

 3. Not producing endospores. 

 4. Atrichous. 



5. Not intracellular parasites. . Family 3. Corynebacteriacea. 



5. Intracellular parasites Family 4. Rickettsiacea. 



4. Peritrichous Family 5. Kurthiacea . 



3. Producing endospores Family 6. Bacillacea. 



1. Gram negative. 



2. Atrichous or peritrichous, requiring com- 

 paratively complicated organic food. 

 3. Not plant pathogens. 

 4. Not fixing nitrogen. 



5. Capable of growth on or- 

 dinary media Family 7. Achromobacteriacea. 



5. Requiring special media; 



minute atrichous pathogens. Family 8. Pasteurellacea. 



4. Fixing nitrogen Family 10. Azotobacteriacea. 



3. Plant pathogens Family 9. Rhizobiacea. 



2. Atrichous, monotrichous, or lophotrich- 

 ous; the atrichous representatives, and 

 many others, can survive with organic 

 foods simpler than carbohydrates, or 

 with none. 



3. Mostly requiring at least carbo- 

 hydrates Family 11. Spirillacea. 



