176 IMPORTANT VARIETIES OF FISSION-FUNGI. 



Micrococcus radiatus (Fliigge) (Ed. iii, p. 179). 



Micrococci of less than 1 //. The deep colonies in the gelatin plate, 

 which are at first granular and sharply outlined, when they come to 

 the surface become surrounded by a ring of pretty rays, which separate 

 a little at the periphery, so that the colony is somewhat irregularly 

 outlined. Later second and third rings of rays may develop. In the 

 gelatin stab culture there is a pointed funnel of liquefaction. From 

 the lower part of the stab horizontal outgrowths radiate, so that the 

 stab appears as if feathered. We have not seen it; description is from 

 Fliigge. The color is described by Flugge as white, with a yellowish- 

 green shimmer. 



Micrococcus luteus (Lehm. and Neum.). 



(Plate 6, i-v. ) 



Synonyms. The insufficiently defined Micrococcus 

 luteus Cohn, designated by Schroter as Bacteridium luteum, 

 is not to be identified as a particular variety. We desig- 

 nate the species to be described in this way, to express the 

 relation to the Sarcina lutea. 



Microscopic Appearance. Medium sized (0.4 /* to 

 1.2 /*), roundish cocci, often lying together in fours, often 

 only in pairs. 



Relation to Oxygen. In shake cultures strongly aero- 

 bic. 



Requirements as to Temperature and Nutrient 

 Media. Grows rapidly and luxuriantly at room and incu- 

 bator temperature upon all nutrient media. 



Gelatin Plate. (a) Natural size : Yellowish to yellow- 

 ish-white irregularly round colonies, after three days from 

 1^ mm. to 2 mm. broad. In a short time they sink in, 

 without the form of the colonies being disturbed. Later 

 there follows a breaking up of the film into irregular gran- 

 ules and debris. 



(fo) Magnified fifty times. Superficial: Yellowish-gray to 

 grayish-brown, irregular, roundish colonies with wavy, 

 scalloped borders. In the periphery, at times individual 

 tetrads are plainly visible. The outer part is more trans- 

 parent than the central portion. The interior is uniformly 

 shaded in a gray color. Deep : Roundish to whetstone- 

 shaped, smooth border, finely granular, of the same color 

 as the superficial (6, n). 



