18 



THE AMERICAN MONTHLY 



[Feb 



smaller (fig. 3, x 2,000 dia.). The long axes are parallel 

 with each other and there are many hundreds of these 

 bacterial lines placed side by side in a single filament 

 which may be called an elongated zoogloea coated with 

 sulphur particles. Do they attract this coating ? Such 

 is the case with the genus Beggiatoa which leads to a be- 

 lief that this is a genus of that species. Some of the 



Beggiatoa even engulph grains of sulphur within their 

 infinitesimal cell-walls. Figure 4 with magnification of 

 500 diameters is known to be a Beggiatoa but fig. 3 when 

 X 2,000 does not give any such detail for the sulphur 

 grains are plainly shown in figure 4. The rod shape 

 proves a bacillus. The attraction for sulphur proves a 

 Beggiatoa. 



These filaments are coated so beautifully with calcium 

 carbonate and sulphur as to appear like icicles in the 



