THE LEUCO-THIOBACTERIA iii 



sulphur contents (Fig. I2a). In older threads a sheath of 

 slime is formed from the outermost layers of the cells, which 



n\ 



9^ 





o 



abed 



Fig. 12. — Thiothrix violacea (Ellis). X 1200. 

 a. — Fragment of old thread made up of the hardened slime sheath, the 



transverse bands of slime, and unidentified particles. 

 b. — Fragment of old thread containing seven round bodies, possibly endo- 



spores. Previously formed transverse bands of slime have been swept 



away by growth in the cells within the hardened sheath. 

 c. — Fragment of a thread with an open end and transverse bands of slime. 

 d. — Thread showing so-called " conidia " formation. The " conidium " 



is attached to the parent thread by a band of slime, which can be seen 



by treatment with carbol-fuchsin. 



subsequently hardens and forms a hollow tube containing 

 the cells in single row formation. In Fig. 12 h and c, are shown 



