I20 SULPHUR BACTERIA 



Virieux claims that nuclear material is present as chromatin 

 granules. If so, their disposition during cell division should 

 be a matter of interest. The method of division is that which 

 is common to the great majority of the sulphur bacteria. The 

 plasma separates without the previous formation in it of a 

 definite cell wall. 



(B) Zoospores. — The cell gradually expands, finally bursting 

 its membrane, and liberating a number of zoospores that, 

 during this period of expansion, have formed inside. Each 

 zoospore resembles the adult in structure, and differs only in 



Fig. 15. — Achromatium oxalijermn. (After Virieux.) 

 a. — Zoospores. They show the diversity of form and characteristic 



alveolar structure of this organism, x 1500. 

 h. — Liberation of zoospores from the nivother cell. X 1000. (For further 



explanation see text.) 



showing some diversity in shape (Fig. 15). It measures 4 — 6/x. 

 in length, although some reach 10 — liju. It exhibits the 

 alveolar structure characteristic of the adult, and in each 

 are 2 — 3 granules and a few corpuscles (see p. 184). Cilia 

 are not developed. The zoospores on liberation increase 

 without any further change to the size of the adult cell. 



Habitat. — Present in water, both fresh and salt, in which 

 H2S is present as the result of vegetable decomposition, and 

 in which also calcium salts are abundant. The organism has 

 been found in various places in Germany (Lauterborn, Frenzel, 

 Bavendamm, etc.) ; in Belgium (Massart) ; in England (West 



