ON SOME NEW MICRO-ORGANISMS OBTAINED FROM AIR. 
2«7 
plaques fringed with brown, which shades off into the surrounding gelatine.' 5 ' As the 
age of the cultivation increases, the brown colour becomes more intense and gradually 
extends throughout the tube. The gelatine becomes slowly liquefied, the fluid being 
of the same dark-brown colour. (See Plate 18, No. lb.) 
Agar-agar .—The surface of the agar becomes covered with flocculent greyish 
plaques around which the brown colour is formed, the latter extending gradually into 
the depth of the tube. (See Plate 18, No. la.) 
Broth .— The appearance is very characteristic. Numerous small, isolated, spherical 
tufts make their appearance throughout the liquid, adhering to the sides and bottom 
of the tube. (See Plate 18, No. lc.) The liquid, wdrich is quite clear, becomes of a 
deep sherry colour. 
Appearance on plate-cultivation .—The colonies appear as cream-white disks, each 
of which is surrounded by a cloud of brown colouring matter extending over a distance 
many times the diameter of the colony. 
Under a low power (x 100) the colony is seen to consist of fine branching threads 
radiating from a central tangled mass. 
o o 
* This surface-growth is of such a tough nature that it is with some difficulty that a portion can be 
removed with a platinum-needle. 
