NON-FILAMENTOUS SULPHUR BACTERIA 281 



object by their ability to proceed at will to the surface of the liquid. Conse- 

 quently this species gains the upper hand in stagnant or quietly flowing waters, 

 in which they search about so eagerly that very little of the oxygen diffusing into 

 the water can reach the bottom where the Thiothrix species rest. The latter, 

 however, have the advantage in rapid running water, the loose Beggiatoa species 

 being washed away by the current. Jn either event, whitish mucinous masses 

 highly characteristic of sulphur springs accumulate in time e.g. those of 

 Bareges in the French Pyrenees and are known in France as baregine or 

 glairine. 



201. Morphology of the Non-Filamentous Sulphur Bacteria. 



Several red species of these organisms are already known to us ( 91), viz., 

 Chromatium (Monas} Okenii, Monas Warmingii, Spirillum rubrum., ^p. volutans, 

 Ophidomonas sanguined, Rhabdomonas rosea. These are again shown in Figs. 74 to 

 78. It was remarked in 68 that Ray Lankester had assumed all these 



FIG. 74 . 



Chromatium Okenii. 

 Magn. 600. (After F. Cohn.) 



FIG. 75. 



Rhabdomonas rosea. 

 Magn. 600. (After F. Colin.) 



FIG. 76. 



Monas Warmingii. 

 Magn. 600. (After F. Colin.) 



FIG. 77. Spirillum volutans. 

 Magn. 600. (After F. Cohn.) 



FIG. 78. Ophidoiuouas sanguine 

 Magn. 600. (After F. Cohn.) 



organisms to be merely special forms of one species for which he proposed the 

 name Bacterium rubescens, The basis for this assumption was, however, a very 

 insufficient one, since it rested principally on the identity (which, moreover, was 

 not satisfactorily demonstrated) of the red colouring-matter, peculiar to these 

 organisms, and which received from Lankester the name bacterio-purpurin. 

 This investigator was supported in his views by Warming (in 1875), wno n 

 his part classified a large number of the red sulphur bacteria examined by him 

 into a single species, viz., Bacterium sulfuratum. Zopf (in 1882) went still 

 farther than either by defining all these organisms as special forms of growth 



