6 Synopsis of the Bacteria and Yeast Fungi. 



Key to the Genera. 



1. Cells round or ovate ... ... ... ... ... 2 



Cells cylindrical ... ... ... ... ... 5 



Cells lanceolate, flat, spirally twisted ... ... Spiromonas 



2. Cells isolated or united in chains or formless gelatinous 



masses ... ... ... ... ... Micrococcus 



Cells united in considerablenumbersin colonies of definite outline 3 



3. Colonies hollow, with a simple peripheral cell-layer... Cohnia 

 Colonies solid, with cells throughout their substance ... 4 



4. Cells united in a small but definite number in regular 



families ... ... ... ... ... Sarcina 



Cells united in a large and indefinite number in irregular 



colonies ... ... ... ... ... Ascococcus 



[Cells in chains, each chain surrounded by a gelatinous 



sheath ... ... ... ... ... Leuconostoc\ 



5. Cells shortly cylindrical, single, or loosely combined in twos 



or a few together ... ... ... ... Bacterium 



Cells long, cylindrical, united in threads ... ... ,., 6 



6. Threads isolated or felted together ... ... ... 7 



Threads enclosed in roundish gelatinous masses ... Myconostoc 



7. Threads unbranched ... ... ... ... ... 8 



Threads with evident branching ... ... ... Cladothrix 



8. Threads straight, or nearly so ... ... ... ... 9 



Threads spirally wound or bent ... ... ... ... 11 



9. Threads conspicuously articulated, rather short ... Bacillus 

 Threads mostly not conspicuously articulated, long ... 10 



10. Threads very slender ... ... ... ... Leptothrix 



Threads thicker ... ... ... ... Beggiatoa 



11. Threads short, with few spirals, or simply bent, rigid Spirillum 

 Threads longer, with numerous spirals, flexile ... Spirochmta 



I. MICROCOCCUS, Cohn ("Beitrage zur Biologic," 

 i. p. 151.) 



Cells colourless or of a pale tint, round or oval-elliptic, 

 motionless, dividing in one direction only. The daughter- 

 cells either soon separate from one another, or remain united 

 in a chain of two or more, or form a zoogloea. Formation 

 of the spores not certainly known. 



