1 66 



SULPHUR BACTERIA 



Both these species have a strong resemblance to some of 

 the phases of Beggiatoa roseo-persichia which were regarded by 

 Zopf as " one of the many kinds of the zoogloea forms of 

 Beggiatoa roseo-persicina.'" Hence this genus is only pro- 

 visionally given a place in this classification. 



a 



Fig. 43. — (a) Thiosphcsrion violacea. (b) Species of ThiosphcBvion (unnamed). 



In Fig. 43& is shown an organism in the zoogloea condition, 

 which appears to belong to the genus Thiosphcurioji. It is 

 made up of globular masses arranged in an irregular fashion, 

 the whole being slightly tinged with red. Each globular 

 mass is about 15/x in diameter, and is composed of a large 



