318 FRESH-WATER ALGJ3 OF THE UNITED STATES. 



Genus 104, BEGGIATOA, Trevis. 



Filaments simple, slender, like Oscillaria, vibrating (?) cell 

 contents colorless. 



The plants of this genus are of doubtful value. The fila- 

 ments are usually clustered and attached, color dull white, or 

 glossy silver or chalk white. They are found in sulphurous 

 waters ; abounding in localities like Clifton Springs, New York ; 

 Sulphur Springs, Niagara; Glen Cove Springs, Florida; arte- 

 sian wells, Florida, and probably more or less in all sulphur 

 springs. The same plants in fresh -water springs would be classed 

 as Leptothrix. The white appearance is abnormal, produced by 

 the chemical action of the sulphur water. Normally the fila- 

 ments are without distinct transverse divisions ; in younger 

 stage, light aeruginous, or light yellowish brown ; after a longer 

 subjection to the action of the sulphur in the water the color 

 disappears, and the filaments become silver white. The cytio- 

 plasm loses its vitality, becomes opaque, white to the unaided 

 eye, but black under the microscope, because it does not trans- 

 mit rays of light ; in this condition it contracts lengthwise, 

 breaks into short sections, equal or subequal to twice as long as 

 wide, producing a semblance of articulation. 



The chemical effect of sulphur springs is to destroy colors, 

 acting as a bleaching agent ; it does not affect all colors equally. 

 Chlorophyl green plants are not usually changed by it, neither 

 decided aeruginous colored plants, as Oscillaria. 



Eabenhorst describes ten or twelve European species of BEG- 

 GIATOA, of which we identify only two forms ; these we retain 

 as representatives of the genus, although we recognize in them 

 mere forms of Leptothrix. 





BEGGIATOA NIVEUM, Bab. 



Usually forming extended caespitose floccose, silver white, 

 glistening strata; filaments slender, indistinctly articu- 

 late when in vegetative condition ; later the cytioplasm 

 solidifies and contracts, separating into parts 1-2 times as 

 long as broad, presenting the appearance of an articulate 

 filament. 



Diameter of filaments, 1-1.5 yu. 



Frequent in sulphur springs, Niagara. 



Syn. Leptonema, nivea, Bab. 



Plate CCVIII, figs. 8, 1). From cliffs, Niagara, dripping 

 sulphurous water. 



