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MRS. G. C. FRANKLAND ARD DR. P. F. FRAXKT.AND 
plentiful deposit of cream-yellow matter, and the surface is covered with a delicate 
dirty-white pellicle, which subsequently becomes faintly cream in colour. 
Appearance on plate-cultivation .— To the naked eye the colonies are visible as 
small pin-heads of a faint orange colour. Under a low power (x 100) they are seen 
to be not perfectly circular, finely granular inside, and wfith a very slightly jagged 
edge. (See Plate 19, No. 4c/.) 
2 . Bacillus Aureus. 
Occurrence .—This was also found forming an orange-coloured pin-head on a 
gelatine-plate, which had been exposed in the same place as the last. 
Microscopic appearance. —With a high power (x 1,000 or 1,500) this is seen as a 
bacillus forming fine graceful threads (see Plate 19, fig. 5, No. 56), which are 
considerably longer than those formed by Bacillus aurescens. In drop-cultivations 
they exhibit vibratory motion only. 
Appearance in Cultivations. 
Gelatine .—There is but little growth in the path of the needle below, but on the 
surface it forms a dry crumpled expansion, which is of a much deeper orange colour 
than B. aurescens. In old cultivations it causes slight liquefaction of the gelatine. 
Agar-agar .— Forms an orange growth, which is less crumpled and less dry in 
appearance, but deeper in colour than that of B. aurescens. (See Plate 19, No. 5a.) 
The cultivations, from which the drawings of these two bacilli were made, w T ere started 
on the same day, and, although all the conditions were precisely similar, the 
difference between the two growths was very marked. 
Broth. —After six days (Aug. 7—13, 1886) it resembles B. aurescens , but the 
deposit and pellicle were deeper in colour. 
Appearance on plate-cultivation .—The colonies differ but little from those of 
B. aurescens, forming pin-heads on the surface, which are, however, of a deeper orange 
colour, and are more rapid in then- growth. See Plate 19, No. 5c. 
3. Bacillus Citreus. 
Occurrence. —This was found producing a yellow pigment on the surface of a 
gelatine-dish which had been exposed to the air in ITyde Park. 
Microscopic appearance. —Under a high power this is seen to be a short fat bacillus 
about one-and-a-half to twice as long as broad. It frequently exhibits a median 
transverse division, which can, however, be only well seen with a very high magnifying- 
power (-^g- oil-immersion), 1,500 times. Sometimes the bacilli hang together in chains 
of three and four. The average length of a pair is about 3'4/r ; the ends are rounded and 
sometimes pointed, especially in those cases where division has taken place. Not 
