38 MYCOLOGY 



Crenolhrix. — The cells are arranged in unbranched threads attachet 

 at one end and enlarging toward the distal extremity. Filament; 

 covered by a rather thick sheath. The reproductive cells are non 

 motile conidia, which on discharge immediately germinate. Crenothri: 

 polyspora in springs and water pipes, where it forms attached sUm} 

 growths. The sheaths in iron waters are impregnated with iror 

 oxidhydrate. 



Phragmidiothrix. — Cylindric cells with delicate, scarcely visibh 

 sheath. The cells of the filament are at first in one plane which latei 

 divide in three directions to form clumps or packets of cells. Latej 

 the single cells round off and become free. Ph. multiseptaia with fila 

 ments 3 to i2;u broad and loo/i long attached to the bodies of crustaceae 



Cladothrix {Sphmrotilus in part). — The fixed and often tuftec 

 filaments form delicate sheaths. The cells are cylindric and by inter 

 calary growth may break laterally through the sheath to form falsi 

 dichotomous branches. Reproduction is accomplished by motil( 

 swarm spores (gonidia) which bear a tuft of flagella a little to one sid< 

 of a pole. Cladothrix dichotoma occurs frequently in stagnant water 

 attached and forming furry growths. The following species occur ii 

 the soil: C. rufida, C. profundus, C. intestinalis, C. fungiformis, whil( 

 C. intrica has been isolated from sea water and sea mud. 



Family 5. TraoBACTEEiACEiE (BeggiatoacEjE). — Cells with sul 

 phur inclusions, unpigmented, or colored rose, red or violet by bacterio 

 purpurin; never green. The plants are generally filamentous witl 

 division transverse to the long axis. 



Thiothrix. — Unequally thick attached filaments encased in i 

 delicate, scarcely visible sheath. Rod-shaped conidia are formed a 

 the ends of the threads. Th. nivea is found in sulphur springs and ii 

 stagnant water. 



Beggiatoa. — Sheathless, free-filamentous bacteria, motile by mean; 

 of an undulating membrane. Cells with included sulphur granules 

 Spore formation unknown. B. alba is found in dirty water, draii 

 water from sugar factories and attached to decayed plants in sulphu 

 springs. B. mirabilis forms white growths on dead marine alg£e. 



The colored sulphur bacteria, sometimes placed in the famih 

 RHODOBACTERiACEiE, belong here. They have rose, red or violet eel 

 contents due to the presence of bacteriopurpurin (see ante). The im 



