On Certain Bacteria from the Air of Keiv York City. 347 



5. 9Ierisiuope(lia tetrageiius (Gaffky). 

 Occurrence. " Micrococcus tetragenus " from Krai's laboratory. 

 3Iorpholo(/y, Micrococci .7-. 8 /^ in diameter, in jjairs, a f ew f ours and irrgul»r 



groups. 

 Biology. Besides the character given in the synopsis, rosalic acid is not 



changed ; on solid media the gi-owth is opaque white ; no surface growth 



on broth. 



6. Micrococcus siiuilis n. sp. 



Occurrence. In tha air of the college hallway. 



MorphoJogy. Large cocci, never (^uite spherical, and frequently divided by a 

 constriction to one side of the middle. Very variable, diameter 1-2//. 

 The cells are larger than the Bacillus diphtheriae and decidedly rounder, 

 more like cocci. 



Biology. Grows very poorly at all temperatures. On agar the gi-owth is ob- 

 scure, narrow, translucent whitish. On the lactose-litmus agar there is 

 faint growth with a slight reddening of the medium ; rosolic acid is not 

 faded. The gelatin colonies are round, opaque white, uncharacteristic. 

 Tliere is little reduction of nitrate, especially marked 37-2° where a dis- 

 tinct test was oljtaiued in twenty days. 



7. Micrococcus conceiitricus (Zimmerman). 



Occurrence. (1) " M. concentricus " from Krai's laboratory. (2) Eighteen 

 different times in the air of the college hallway. 



Morphology. Micrococci .6-1.2// in diameter, singly, in twos, in short irregu- 

 lar chains or in masses. 



Biology. Well distinguished by its power of decolorizing ro.salic acid. The 

 growth on solid media is rather translucent white, sometimes concentri- 

 cally marked. On liquid media the growth is soft and somewhat stringy, 

 often forming around the surface on the glass. Growth on potato abund- 

 ant, shining sordid wliite. 



8. Micrococcus cereus aureus n. sp. '? 



Occurrence. (1) "Staphylococcus* cereus aureus" from Krai's laboratory. 



(2) A contamination from the air of the laboratory. 

 3Iorphology. Cocci .l-.S,u in diameter, singly, in pairs, threes or masses. 

 Biology. On agar and potato shining bright orange. In brotli a hea^-j- orange 



colored s.ediment with no surface growth. 

 Remarks. I have seen no description with the above name, iinder which the 



culture was received. This is only a variety of the following species, 



whicli is the non-chromogenic form. 



9. Micrococcus cereus albus (Passet). 



Occurrence. (1) " Staphyloccocus cereus albus " from Krai's laboratory. (2) 

 In the air on 59th St. 



*0f all the generic terms proposed for the various associations of the cocci, probably 

 " Staphylococcus " is the least valuable. I would definitely discard it. 



