510 MICRO-ORGANISMS IN WATER 



BEGGIATOA ROSEO-PERSICINA 



Authority. Cohn, Beitrage, vol. i., Heft iii., p. 157 ; Lankester, Quart. Journ. 

 of Mic. Science, 1873, vol. xiii. p. 408. 



Where Found. In polluted ponds and ditches, covering the surface with a 

 red or violet growth. Often noticed on the Danish sea-coasts. The filaments 

 resemble B. alba in shape, but are distinguished from the latter by their reddish- 

 violet colour. The cocci, which are produced in the filament, multiply by 

 division, and form characteristic zooglaa masses of various shapes, branched, 

 lobular, and netted. Eods, under certain circumstances, develop from the 

 cocci, and, on the dissolution of the gelatinous envelope, both cocci and rods 

 may come forth. The rods form filaments, which may be partially or entirely 

 spiral in form. The cells composing the zooglcea are round or oval, red in 

 colour, and are 2-5 p. in diameter. 



BEGGIATOA MIEABILIS 



Where Found. In sea-water, forming white growths on decaying algse, 

 sea-grass, &c. Distinguished from other forms of Beggiatoa by its remarkable 

 transverse diameter of 30 /n. 



THIOTHRIX 



Authority. Winogradsky, ' Ueber Schwefelbakterien,' Botanische Zeit- 

 img, 1887 ; also ' Sur la Morphologic et la Physiologic des Sulfobacteries,' 

 Beitrdge z. Morphologic und Physiologic d. Bacterien, fasc. i., Leipzig, 1888 ; 

 also ' Kecherches physiologiques sur les Sulfobacteries,' Annales dc Vlnstitut 

 Pasteur, vol. iii., 1889, p. 49. 



Where Found. In sulphur springs along with other forms of Beggiatoa, 

 from which Winogradsky distinguishes them by the unequal thickness of the 

 filaments and by the production of motile gonidia. 



Winogradsky, in his Memoirs, states that it is exceedingly difficult to grow 

 Beggiatoa and Thiotrix artificially, as they die rapidly on all solid media and 

 only develop well in waters containing sulphuretted hydrogen. He mentions 

 incidentally that contact with distilled water rapidly kills the filaments ; they 

 become at once motionless, twist, break, sometimes swell up, and then begin 

 to decompose. (Annales dc VInstitut Pasteur.} 



