LEPTOTRICHE.^E AND CLADOTRICHEJE. 705 



they are able to multiply abundantly in. thermal sulphur waters having a 

 temperature of 55 C. and above. 



433. BEGGIATOA ALBA (Vauch.). 



This is an extremely common and widely distributed species ; found es- 

 pecially in thermal waters and in the refuse waters from sugar refineries 

 and factories of different kinds. 



Morphology, The filaments differ greatly in diameter as well as in length 

 from 1 to 5 M in diameter; the young and slender filaments often contain 

 hut few grains of sulphur or none at all; the older filaments usually con- 

 tain a considerable number of fine or coarser granules of sulphur. The 

 filaments, which are attached to some substance, are usually seen to be seg- 

 mented, even without the use of reagents, at least near the base where the 

 grains of sulphur are less numerous or absent ; the free ends, containing 

 numerous grains of sulphur, may not appear to be segmented, but when, 

 they are stained with one of the aniline colors, or treated with hot glycerin, 

 segmentation becomes apparent. In the thicker threads the segments divide 

 into thin discs, and these again, under certain circumstances, divide, in a di- 

 rection parallel with the long axis of the filament, into quadrants, each of 

 which later becomes a spherical or ellipsoidal coccus; these usually contain 

 one or several large grains of sulphur. These cocci remain attached for a 

 time, then under favorable conditions become separated and enter upon the 

 " swarm stage " of their existence, during which they are endowed with ac- 

 tive movements. They come to rest upon some filament of an alga or other 

 substance, which may be completely covered, and has a dark color as a re- 

 sult of their presence. They multiply by binary division and form zooglcea 

 masses of irregular form. Under certain circumstances they form straight 

 or curved rods, which may also exhibit active movements. When these 

 come to rest they grow out into long filaments, which may be straight or 

 spirally curved. Fragments of the spiral filaments may, under certain cir- 

 cumstances, become actively motile and resemble genuine spirilla; their 

 movements are due to the presence of terminal flagella. The diameter, 

 length, and the height of the spiral turns vary greatly. The straight fila- 

 ments also show a decided tendency to break up into longer or shorter frag- 

 ments, but these do not exhibit active motions; they, in common with the 

 fragments of spiral filaments, are, however, flexible and exhibit " crawling " 

 motions. 



434. BEGGIATOA ROSEO-PERSICINA (Zopf). 



Synonyms. Clathrocystis roseo-persicina (Cohn) ; Ophidomonas san- 

 guinea (Ehrenberg) ; Bacterium rubescens (Lankester). 



Found upon the surface of putrefying animal or vegetable material in 

 fresh or salt water. 



Morphology. Presents the same developmental forms as Beggiatoa alba, 

 viz., cocci, rods, filaments, and spiral threads. The filaments correspond 

 with those of Beggiatoa alba, but are distinguished by their red or violet 

 color. The cocci, formed in the filaments, when set free undergo binary 

 division and form characteristic zoogloea of very various forms ; these were 

 formerly described by Cohn under the name of Clathrocystis roseo-persi- 

 cina. These zoogloea may be spherical, oval, irregularly branched, etc. ; at 

 one time they may contain but a little, and at another considerable gela- 

 tinous intercellular material. Rods are developed from the cocci under cer- 

 tain circumstances, which may be straight or curved. In suitable media 

 both the cocci and the rods, after the intercellular substance is dissolved, 

 may become actively motile " swarm stage." The short rods grow out into 

 filaments, and these may, under certain circumstances, become spiral in 

 form, either partially or entirely; the spiral filaments may break up into 

 onotile fragments which correspond with Ophidomonas sanguinea of Ehren- 



