ON SOME NEW MICRO-ORGANISMS OBTAINED FROM AIR. 
273 
unfrequently there are found forms of very peculiar shape. Some are bent and often 
club-shaped, and present other irregularities in thickness. That these forms are only 
modifications of the same organism is distinctly proved by the fact that they are found 
along with the ordinary forms in one and the same colony when the organism is 
submitted to plate-cultivation. These forms do not appear to be due to involution, as 
they occur in fresh cultivations and stain well. Neither were spores observed in these 
nor in any of the other forms. A very large number of microscopic preparations were 
made from different cultivations of this organism in order to confirm these observa¬ 
tions. (See Plate 20, fig. 2, No. 2 b.) 
In drop-cultivations the bacillus is seen to be non-motile. 
Appearance in Cultivations. 
Gelatine. —After four days (August 6—10, 18S6) the needle-track below presents a 
slight saw-like growth, whilst on the surface there is a small leaf-like expansion 
extending on either side of the needle-streak. (See Plate 20, No. 2a.) This 
expansion is of a distinct lemon-yellow colour, with a smooth shining surface. The 
growth does not extend much on keeping the cultivation longer, and no liquefaction 
of the gelatine takes place. 
Agar-agar. —Forms a moist shining surface-expansion of sulphur-yellow colour, 
and with a lobular edge. The growth, even in old cultivations, was not found to 
extend over the whole surface. 
Broth. —After nine days (August 7—16, 1886) the liquid is clear, free from pellicle, 
and has a very slight yellowish deposit at the bottom. 
Appearance on plate-cultivation. —The colonies are visible to the naked eye as 
small white discs after four days, which, on keeping longer, become of a strong 
vellow colour. 
•/ 
Under a low power (x 100) the colonies are seen to be highly granular, more or 
less regularly circular in shape, and with an almost smooth edge. (See Plate 20, 
No. 2c.) 
4. Bacillus Plicatus. 
Occurrence.- —This was found forming a white irregular protuberance on the surface 
of a gelatine dish which had been exposed to the air in one of the wards of the 
Brompton Hospital for Consumption. 
Microscopic appearance. —Under a high power this is seen to be a very minute 
bacillus, about lj> times as long as broad. Usually several bacilli are adherent 
together, thus forming short threads (see Plate 18, fig. 7, No. 7b), the length of which 
varies from 1'7/x to 5/x. 
Seen in drop-cultivations, it was found to be very motile. No spore formation was 
observed. 
M DCCCLXXXVII. —B. 
2 N 
