ON SOME NEW MICRO-ORGANISMS OBTAINED FROM AIR. 
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9. Bacillus lsevis. 
10. ,, cereus. 
11. ,, subtilis. 
12. ,, (Micrococcus) prodigiosus. 
The above is a list of the various forms of bacilli which have been found by us in 
air, and which, with the exception of the two last, have not, as far as we are aware, 
been previously described. We have again ventured to designate these new forms by 
names which are indicative of some striking characteristic which they possess. Thus 
in the case of Nos. 1, 2, 3, and 5, the pigments which are produced on cultivation 
being very marked, the names have been selected with I’egard to this property. In 
the case of No. 4, again, the peculiar appearance of the cultivations is suggested 
in the name; whilst in No. 7 the microscopic appearance, and in No. 8 the strong 
and highly disagreeable smell possessed by its cultivations, are indicated by the 
names assigned to them. 
1 . Bacillus Aurescens. 
Occurrence. —This was met with by us as a yellow growth on a gelatine-dish 
which had been exposed to the air of a railway-carriage. 
Microscopic appearance. —Under a high power (x 1,000 or 1,500) tins is seen to 
be a short bacillus occurring singly, in pairs, and in threads of three and four. The 
individual bacilli are from three to live times as long as broad, with rounded ends. 
Their length varies from 1'5/x. to 3’5/r. In the threads the divisions are not always 
distinctly visible, and it has then the appearance of a long slender bacillus. In 
Plate 19, fig. 4, No. 4 b, the appearance of the bacilli when grown in broth is 
represented, the magnifying power being 1,000. In No. 4c the bacilli are taken from 
a gelatine-cultivation, and are only magnified about 600 times. 
Viewed in drop-cultivations, they exhibit vigorous vibratory and rotatory motion, 
but no movement of translation was observed. 
Appearance in Cultivations. 
Gelatine. —The growth is very faint in the track of the needle below, but on the 
surface it forms alight orange-coloured, dry, and much crumpled expansion, which does 
not cause liquefaction of the gelatine even in very old cultivations. The appearance 
is very characteristic. 
Agar-agar Forms a dry light-orange surface-growth, much crumpled, with an 
irregular edge, which is of lighter colour than the central portion. (See Plate 19, 
No. 4a.) 
Broth. —After six days (August 7—13, 1886) the liquid is clear, but there is a 
