MICROCOCCI IN THE AIR 107 



work of fibres likewise runs into the substance of the gela- 

 tine without liquefying it. 



Micrococcus ureae. — This is a micro-organism which 

 does not liquefy gelatine, and which, although it occurs in 

 the air, can also be obtained from decomposed ammoniacal 

 urine. It was described by Pasteur and Van Tieghem. 



The cocci are for the most part arranged in pairs, and 

 when they have grown for a considerable time upon gelatine, 

 show a rather large-sized colony 

 which is raised above the surface 



like a drop of solidified stearine, I' •■p^'&^^^k 



and diffuses a smell like that of s!.^c^^rrT^fi-iif''^ry 



paste. It sets up fermentative j.^^. 34.-micbococous uee^e. 



. -J (Alter Jaksch.") 



processes m urme, owmg to its 



property of converting urea into ammonium carbonate. 

 Growth takes place at room-temperature, or best at 30° C, 

 but it does not lose the power of development even at 

 temperatures below zero (fig. 34). 



Micrococcus roseus. — This is a micrococcus occurring in 

 gonorrhoeal disease of mucous membranes, and was found 

 in the air by Bumm. The cocci are immotile, and are 

 arranged in pairs, each half of the diploccocus so formed, 

 being hemispherical, and separated from the other by a 

 fissure. The small colonies formed by it on the gelatine 

 plate are rose-red and raised above the surface. Thrust- 

 cultures show liquefaction of the gelatine, but only .after a 

 considerable time, and a rose-red colour then forms at the 

 bottom of the needle-track. 



Diplococeus citreus conglomeratus. — This micro-organism 

 was found by Bumm in the dust of the atmosphere, with 

 which it probably enters the human organism. Its elements 

 are not motile, and are sometimes arranged in pairs, at 

 other times in fours. They form small oblong colonies on 

 the gelatine plate, which soon become fissured, and possess 



