THIOTHRIX 511 



THIOTHRIX NIVEA (Beggiatoa nivea, Rabenhorst) 



Authority. Eabenhorst, Kryptogamenflora, vol. i., Pilze, von Winter, 

 Leipzig, 1881 ; also Winogradsky, loc. cit. 



Where Found. Frequently in either sulphur or stagnant water. 



Microscopic Appearance. Motionless filaments surrounded by a thin 

 sheath and attached by one extremity. This extremity, which is the base, is 

 2 to 2'5 IM broad, whilst the free extremity is 1-4 to 1*5 /* broad. They may reach 

 100 n in length and are segmented at the free extremity, where rods 8 to 9 p. long 

 form successively and become liberated in the liquid and exhibit motility. 

 These are the Gonidia, and are never found in the true Beggiatoa. These 

 Gonidia become attached, lose their motility, and then reproduce filaments. 



THIOTHRIX TENUIS (Winogradsky) 



Where Found. -In sulphur water. 



Microscopic Appearance. Forms very long filaments, the diameter of 

 which is almost uniformly 1 /u only. 



THIOTHRIX TENUISSIMA (Winogradsky) 



Where Found. In sulphur water. 



Microscopic Appearance. Keceives the above name on account of its very 

 attenuated filaments, which are not more than 0*5 p. broad. 



CRENOTHRIX 



This species differs from the Beggiatoa by the invariable presence of a 

 sheath which surrounds the filaments ; this sheath is more or less thick and 

 has a great affinity for oxide of iron, which it fixes. No sulphur granules are 

 found in the protoplasm. 



