350 GENERAL SYSTEMATIC BACTERIOLOGY 



unbranched, without sulphur granules and in filaments. He con- 

 cludes that Gallionella and Spirophyllum are growth forms of this 

 genus. 



Heim (1911, p. 254) again emphasizes the L. buccalis type. He says: 



Diese in der Mundhohle anzutreffenden Mikro-organismen sind steife, unverz- 

 weigte, fadenahnliche Gebilde, die sich mit Jodlosung gelb farben. Es gibt 

 auch fadenartige Mikroorganismen, die sich mit Jod violett farben; sie sind bei 

 Munderkrankungen wiederholt in kornerartigen Gebilden gefunden worden, die 

 in ihrem Aussehen an Aktinomyzeskorner erinnerten. Genaueres liess sich iiber 

 sie nicht ermitteln, weil ihre Ziichtung bis jetzt nicht gelungen ist. 



The legitimacy of L. ochracea as a species name is disputed by 

 Molisch, who reduces this designation to a synonym of Chlamydothrix. 



In a careful study of the organisms of the teeth Kligler (1915, p. 328) 

 cultivated fifteen strains of Leptothrix buccalis, and used this designa- 

 tion. His characterization is as follows: 



Morphology. A thick, long, straight, or curved thread with a club-head at one 

 extremity and a tapering end at the other. It is generally 0.8-1/x thick and 

 upwards of lO/x in length. Chromology. It stains readily with anilin dyes in 

 young cultures. In older cultures it has the appearance of a faintly stained 

 sheath enclosing a number of heavily stained granules. Young cultures are 

 Gram-positive. In older cultures the sheath is decolorized while the granules 

 retain the stain. It is not pleomorphic but the threads fragment very early into 

 short, thick rods. Coccoidal forms are not seen. Biological properties. They 

 are anaerobic, facultative-aerobic, non-motile, non-branching threads. They 

 grow at 37°C. and practically not at all at 20°C. Cultural characters. No growth 

 is obtained on agar. On glucose-agar-plates they give minute pin-point colonies 

 after 3 to 4 days' incubation. Examined microscopically with a low power, they 

 have a dark center with hairy outgrowth. They grow fairly well in serum-glu- 

 cose-agar, best in the stab and only sparsely on the surface. The surface colony 

 is raised, round, whitish, lustrous, rarely more than 0.5 mm. in diameter. The 

 addition of salivary mucinate to ordinary agar renders the latter a very favorable 

 medium, a thin, grayish, white, spreading growth being obtained in 24 hours. 

 Glucose, sucrose and maltose are fermented, but lactose is not attacked. Gela- 

 tin is not liquefied and neither indol nor ammonia is produced. 



It is evident from the preceding discussion that the name Lepto- 

 thrix has been used in four different ways: 



1. Leptothrix. A genus of algae which may or may not include L. ochracea. 



2. Leptothrix. A genus of iron bacteria with type L. ochracea. 



3. Leptothrix. A genus of elongate bacteria, principally from the mouth, 

 with L. buccalis as the type. 



4. Leptothrix. Any elongate, rod-shaped organism. 



