ON SOME NEW MICRO-ORGANISMS OBTAINED FROM AIR. 
267 
but clear below, with a dirty white deposit at the bottom. After eighteen days the 
deposit has become of an orange colour. 
Ap>p>earance on plate-cultivation. —To the naked eye the colonies are visible on 
the fifth day (October 13—18, 1886) as small, round, yellow colonies, each of which 
exhibits a circular surface-depression of varying size. On examination with a low 
power ( X 100), the colonies are seen to be circular and granular, with a slightly denti¬ 
culated edge, which in the less developed colonies is not so marked. (See Plate 18, 
No. 4c.) 
6 . Sarcina Liquefaciens. 
Occurrence. —We have found this organism in the air collected on the roof of the 
Science Schools, South Kensington Museum. It was particularly abundant on the 
8th July, 1886, when it was found producing small granular liquefying colonies on the 
surface of gelatine-dishes which had been exposed there. 
Microscopic appearance. —Under a high power ( X 1,000 or 1,500) it much resembles 
Sarcina lutea, the cocci, which are about 1'5/x in diameter, being arranged in packets 
of four and upwards, a very large number sometimes remaining aggregated together. 
(See Plate 18, fig. 5, No. 5b.) 
Appearance in Cultivations. 
Gelatine. —After four days (August 6—10, 1886) the needle-track below is 
composed of small isolated whitish centres, whilst above there is a large depression 
with an air-space and cloudy liquid contents, at the bottom of which there is 
a greyish-white deposit. The liquefaction has not extended across the tube. On the 
ninth day (August 6—15) the liquefaction has extended across the tube to depth 
of about half-an-incli (see Plate 18, No. 5a), the liquid portion being very turbid, 
with a yellowish-white deposit resting upon the surface of the still solid gelatine 
below. The lower portion of the needle-track exhibits no material alteration. 
Subsequently the liquid portion becomes quite clear. 
Agar-agar. —The growth is very rapid, producing an almost colourless (very 
faintly green) expansion, very much resembling that of Sarcina aurantiaca, excepting 
as regards the colour. 
Broth. —After nine days (August 7—16, 1886) the liquid is clear, free from pellicle, 
and with a dirty-white deposit at the bottom, which subsequently becomes of an 
orange colour. 
Appearance on plate-cultivation.- —To the naked eye the colonies appear almost 
colourless (very faintly green). They had not caused liquefaction of the gelatine on 
the fifth day (October 13—18, 1886) ; a day later (October 19) they formed a surface- 
depression like Sarcina aurantiaca. Under a low^ power (x 100) the colonies appear 
(see Plate 18, No. 5c) as highly irregular in contour, with a denticulated end lobular 
edge and granular contents. 
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