CLASSIFICATION OF BACTERIA 39 



portant genera according to Erwin F. Smith ("Bacteria in Relation to 

 Plant Diseases," I: 163) are Thiocystis, Thiocapsa, Thiosarcina, 

 Lamprocystis, Thiopedia, Amcebobacter, Thiolhece, Thiodictyon, Thiopoly- 

 coccus, as well, as the three genera Chromatium, Rhabdochromatium, 

 Thiospirillum. 



Family 6. Actinomycetace.« (Position doubtful). — Radially ar- 

 ranged branched filaments in colonies, non-motile. Filaments divid- 

 ing into oidia-like reproductive cells. 



Actinomyces chromogenes occurs in soil. A. bovis is the cause of 

 lumpjaw in cattle and occasionally in man. The plant occurs in 

 rosettes usually 30 to 40/i in diameter. The filaments which are often 

 curved sometimes spirally exhibit true branching and are interlaced 

 in a network. Recently Youngken (Amer. Jour. Pharm., September, 

 1915) has described the foundation of the large swellings (mycodomatia) 

 on the roots of the waxberry, Myrica carolinensis, and other species, as 

 due to a species of ray fungus, Actinomyces myricarum, that abun- 

 dantly fills infested cells in the cortex of the tubercular swellings. A . 

 thermophilus is found on hay and manure. 



ORDER II. MYXOBACTERIALES.— Individual plants en- 

 closed in slimy masses which assume more or less regular fructifica- 

 tion-like shapes. 



Family i. Myxobacteriace^. — Erwin Baur and Roland Thaxter 

 have studied these forms most intimately. The plants of this family 

 consist of motile, rod-like microorganisms, with a gelatinous base and 

 forming false plasmodioid aggregations preceding a cyst-producing, 

 quiescent state in which the rods may be encysted in groups or con- 

 verted into spore-masses. The slightly reddish rods in the vegetative 

 stage are elongate, sometimes rs^i long and vary little in size in the 

 different genera and species. Cell division is by fission and the active 

 rods show a slow sliding movement without organs of locomotion. The 

 vegetative phase in artificial cultures usually lasts about a week, or 

 even two weeks, and the formation of cysts which follows must be more 

 rapid in nature. These organisms are found in moist places on decay- 

 ing wood, dung, funguses and hchens, growing best, according to Baur, 

 at 30°C. Three genera are included in this family. 



Chondromyces: — Rods producing free cysts within which they 

 remain unchanged. The cysts are various, sessile or developed on a 

 stalk (cystophore). 



