THE LEUCO-THIOBACTERIA 



125 



longer, and there is more to be lost than gained by unnecessarily- 

 adding to the number of species. 



The cells show quick, agile movements and appear to be 

 devoid of cilia. Reproduction is by longitudinal fission. The 

 intimate structure of the cell is given on page 185. Hinze 



Fig. 18. — Thioviilum Miilleri. X 2000. 



claims that a certain organ in the cell which is colourless, but 

 which possesses a centrum that can be stained with Delafield's 

 hiematoxylin, is a nucleus, and that cell division is accompanied 

 by the division of this organ (see Fig. 19). He also states 

 that when the HgS supply is scarce, starch or an amyloid 

 compound is stored in the cell, probably as a food reserve. 

 An interesting feature in 

 Hinze's work is his observa- 

 tion that the cells are still in 

 possession of a large number 

 of sulphur granules when, after 

 an active life, they have come 

 to rest and apparently died. 

 Thus there are other determin- 

 ants besides sulphur in the 

 metabolism of this organism. 



Habitat. — Found on the 

 Danish coast, in various parts 

 of Germany, in Austria, and in the Gulf of Naples. It is 

 probably an organism of universal distribution. It lives in 

 water above mud rich in sulphuretted hydrogen, and thrives 

 particularly well in salt water, although it is also found in 

 fresh waters. 



Fig. 19. 



-Thiovulum Miilleri. 

 X 1500. 



