268 
MRS. G. C. FRANKLAND AND DR. P. F. FRANKLAXD 
Distinctive Differences existing betiveen the three Forms of Sctrcina described. 
Under the microscope the Sarcinci ciurantiaca is sharply distinguished from the other 
two by the smaller size of its cells, whilst it presents a still more striking contrast to 
the other two in the colour of the pigment which it produces when cultivated in 
gelatine or on agar-agar. From Sarcina Intea the other two are also distinguished by 
the far more rapid liquefaction of the gelatine which they produce. The property 
which the almost colourless Sarcina has of liquefying right across the tube presents a 
marked point of distinction from Sarcina aurantiaca, in which the liquefaction takes 
place in the form of a bag. 
7. Micrococcus Gigas. 
Occurrence .—This was found by us in the air of a cow T -shed, forming a large white 
expansion on a gelatine dish exposed there. 
Microscopic appearance .—Under a high power ( X 1,000 or 1,500) this is seen to he 
a large micrococcus, sometimes as much as 1‘7/x in diameter ; the cocci are frequently 
adherent in pairs. (See Plate 17, fig. 3, No. 3a.) 
Appearance in Cultivations. 
Gelatine. —It liquefies the gelatine slowly, rendering it turbid. 
Agar-agar. — It forms a yellowish-white smooth surface-growth, extending in 
lobules to right and left of the needle-streak. Later on, the colour becomes cream- 
yellow, and the lobules, which are numerous, remain small. There is a considerable 
granular growth in the track of the needle beneath the surface. 
Broth. —After six days (September 7—13, 1886) the liquid is clear, free from 
pellicle, and has a whitish deposit at the bottom. 
Appearance on plate-cultivation. —After four days the colonies appear on the 
surface as pin-heads of a faint cream colour, each causing a depression in the gelatine. 
Under a low power (x 100) the colonies are seen to be circular in shape, with a 
slightly irregular edge, and the contents, which are cloudy at the centre, become 
distinctly granular towards the edge. (See Plate 17, No. 36.) 
8 . Micrococcus Chryseus. 
Occurrence. —This was found by us in the air collected on the roof ol the Science 
Schools, South Kensington Museum. 
Microscopic appearance. — Under the high power (x 1,000 or 1,500) it appears as 
a micrococcus of variable size, up to lg in diameter ; the largest cells exhibit a division. 
The cocci are not arranged in any definite manner. (See Plate 19, fig. 3, No. 3a.) 
