446 GENERAL SYSTEMATIC BACTERIOLOGY 



into families), not capable of swarming (non-motile). In mass the 

 organisms are cherry red. Contain sulphur granules." 



Bergey et al. (1923, p. 404) follow Buchanan. 



Rhodococcus. This generic name has been introduced three times 

 into bacteriological nomenclature. It was first used by Zopf (1891, 

 p. 28) to apply to two species of red bacteria whose physiological 

 characters had previously been studied at length by Overbeck (1891, 

 p. 399). These organisms had been known as Micrococcus erythro- 

 myxa and M. rhodochrous. He characterized the genus (or subgenus 

 as he terms it) as follows: 



Colonien auf gewohnlicher Nahrgelatine gebirgsriickenartig; roth gefiirbte 

 Zellen weder ausgesprochen fadige noch flachenformige oder korperliche Ver- 

 bande bildend, sondern unregelmiissig zusammengelagert, ohne GallerthtiUe, 

 einen rothen Fettfarbstoff enthaltend, der nach der Ausscheidung in rothen, 

 auffalligen Aggregaten krystallisirt, und durch ein einziges breites Absorptions- 

 band bei F. ausgezeichnet ist. 



The species Rhodococcus erythromyxa was isolated by Zopf from tap 

 water. Overbeck describes it as producing round sharply circimiscribed 

 red colonies in plate cultures. In stab cultures in agar and gelatin 

 growth occurs only in the upper portion of the stab. Grows well on 

 potato, egg, etc., forming an abundant red pigment, cultures generally 

 being slimy. Cells are about Ll/x in diameter, spherical. In general 

 they are grouped irregularly, but packets are sometimes formed in 

 suitable media. Gelatin is not liquefied. The pigment was deter- 

 mined to be a lipochrome. 



These species are disposed of in various ways of subsequent authors. 

 Migula (1900, p. 487) uses the designation Bacterium erythromyxa 

 (Zopf) Mig. Matzuschita (1902, p. 389) changes it to Bacillus ery- 

 thromyxa, because of its shape. He (p. 441) however uses the name 

 Micrococcus rhodochrous. He describes it as 



Grosse Zellen. Kleine, mattglanzende, kreisrunde gewolbte, dunkelkarminrosa 

 gefarbte Kolonien. Auf Agar erst karminrosa, dann tief zinnoberrote Aufla- 

 gerung. In Bouillon bild er sich eine dicke rosa Haut, glatt, feucht und ein 

 roter flockig — brockeliger Bodensatz. 



This shows that at least one of the species is a true coccus. It would 

 seem evident therefore if the red pigmented cocci are worthy of generic 

 designation, that Rhodococcus Zopf is valid. 



Winslow and Rogers (1906, p. 546) evidently without knowledge of 

 the previous use of the name by Zopf, proposed Rhodococcus as a generic 



