THE PRINCIPLES OF CLASSIFICATION gi 



Family 3. Rhodothiospirillacece. — Free, spiral, cells ; polar 

 ciliation. 

 Genus i. Rhodothiospirilhim, as for family. 



Family 4. Rhodocapsacece. — Free cells each surrounded by 

 slime ; motile. 



Genus l. Rhodocapsa. — Uni- or diplo-cocci, or short 



chains. 

 Genus 2. Rhodothece. — Rod cells ; contain aerosomes. 

 Genus 3. Rhodosarcina. — Cocci arranged in packet form. 



Family 5. Thiocapsacece. — Globular cells, forming clusters 

 enclosed in slime. 



Genus I. Thiocapsa. — Cells non-motile on escape from 



slime. 

 Genus 2. Thiocystis. — Cells motile on escape from slime. 

 Genus 3. Thiospharion. — Violet colour ; slime colonies 

 of globular form ; cells motile on escape from slime. 



Family 6. Amahobacteriacece. — Rods or spherical cells en- 

 closed in slime ; cells connected by plasma threads. 



Genus i. Amcehobacter. — Sphaeroidal cells in slime 

 which move in unison when they separate or close in. 



Genus 2. Thiodictyon. — Rod cells united like a Hydro- 

 dictyon net. 



Family 7. ThiopediacecE. — Globular cells in slime arranged 

 in regular formation. 



Genus i. Thiopedia. — As for family. 



