994 COMPREHENSIVE KEY 



31. Spherical cells 1 to 2 microns in diameter, 2 to 60 or more cells occurring in a primary 



capsule 10 to 20 microns wide; secondary capsules unite to form a mucilaginous 

 colony; iron or manganese compounds are stored in the secondary capsules. 



Siderocapsa p. 218 



Cells coccoid to ovoid, 4.8 to 5.0 by 6.5 microns, forming short chains embedded in a 



thin mucilaginous layer; iron compounds stored in the surface membrane of the cells 



Sideronema p. 220 

 Cells rod-shaped, 2.5 by 6 to 15 microns, straight or slightly bent; not encapsulated; 

 iron or manganese stored on the surface or in the membrane of the cell 



Siderobacter p. 226 



32. Strict intracellular parasites occurring in the cytoplasm of conjunctival cells in cattle, 



goats and sheep. Elliptical, coccoid, rod-shaped and comma-shaped cells occur 



Colettsia p. 961 



(See Manual keys for the class Microtatobiotes) p. 933 



Spherical cells produced in macroscopic fruiting bodies on decaying vegetable material 

 or in culture; fruiting bodies sessile or nearly so. The cocci germinate to produce 

 rod-shaped cells which glide on a solid surface; not flagellated 



Myxococcus p. 883 



Or Chondrococcus p. 886 



(See Manual keys for the order Myxobacterales) p. 858 



Pleomorphic cultures consisting of large and small cocci and small rod-shaped cells 

 which are motile by means of a single polar flagellum; strongly halophilic, requiring 

 20 to 30 per cent salt for optimum growth; Gram-negative Halobacterium 



(H. cutirubrum) p. 207 

 Not as above 33 



33. Cells spherical to ovoid, varying from spheres 5 microns in diameter to large cylindrical 



organisms 35 to 100 microns long; sulfur deposited internally when growing in the 

 present of hydrogen sulfide. In one of the two recorded species, large crystals of cal- 

 cium carbonate fill the cells; motile with a slow jerky rotating action when in con- 

 tact with solid surfaces Achromatium p. 852 



Cells spherical to ovoid, 5 to 20 microns in diameter, with the cytoplasm compressed in 

 one end of the cell; sulfur deposited in the cytoplasmic layer; exhibits an extremely 

 rapid darting motion in free solution suggestive of flagella, which have never been 

 demonstrated; found in waters containing hydrogen sulfide, forming a tenacious 

 web-like growth in a zone of critical hydrogen sulfide-oxygen concentration 



Thiovulum p. 81 



Not as above 34 



34. Cocci varying in diameter from 0.5 to 4.0 microns; grow in a mineral salts bicarbonate 



medium with formate as the only known source of available carbon, fermenting it to 

 methane, CO2 and possibly hydrogen; pH range, 7.4 to 9.2 



Methanococcus p. 1^73 

 (M. vannielii) 

 Not as above 35 



35. Spherical cells 36 



Rods, curved or straight 43 



36. Arranged in cubical packets Sarcina p. Ifil 



Not as above 37 



37. Motile by means of peritrichous fiagella 38 



Non -motile 40 



38. Gram-positive; cells occur in irregular clusters Micrococcus p. 1^55 



(M. cryophilus) 

 Gram-negative 39 



