466 R. E. BUCHANAN 



Tribe I. Thiocapseae Trib. nov. 



Synonyms : 



Thiocapsaceae Migula, 1900, p. 1042 



Bacteria containing both sulphur granules and bacteriopurpurin. 

 Cells divide in three directions of space, united into families. 



Key to the genera of the Thiocapseae 



A. Cells capable of swarming. 



I. Families small, compact, enclosed singly or several together in a 



cyst Genus I. Thiocystis 



II. Cells large, 7 to 8m loosely bound by gelatin into loose families 



Genus II. Thiosphaera 

 III. Cells small, united into solid, spherical families. 



Genus III. Thiosphaerion 



B. Cells not capable of swarming. 



I. Spherical cells spread out upon the suljstratum in flat families, loosely 



enveloped in a common gelatin Genus IV. Thioeapsa 



II. Arranged in regular packets like Sarcina Genus V. Thiosarcina 



Genus I. Thiocystis Winogradsky, 1888, p. 60 



Usually 4 lo 20 or SO cells massed into small, compact families, 

 enveloped singly or several together in a gelatinous cyst, capable 

 of swarming. When the families have reached a definite size they 

 escape from the gelatinous cyst, the latter either swelling and soften- 

 ing uniformly or at some particular spot. The escaped cells either 

 pass into the swarm stage or unite into a larger fused complex of 

 families. Cells are light colored, single cells almost colorless. 

 In masses the cells show a beautiful violet or red violet color. The 

 cells are frequently quite filled with sulphur granules. 



The type species is Thiocystis violacea Winogradsky. 



Genus II. Thiosphaera Miyoshi, 1897, p. 170 



Cells spherical-ellipsoidal, relatively large (7 to S/x) light violet 

 in color, bound into loose families by a colorless gelatin. Capable of 

 swarming. Sulphur inclusions relatively abundant. 



The type species is Thiosphaera gelatinosa Miyoshi. 



