1888 - 89 .] Messrs Macleod and Milles on Asiatic Cholera. 19 
the edge of the colony is finely notched. In a gelatine tube there 
forms a funnel-shaped cavity at the top of the puncture made by 
the inoculating wire, and lying in this cavity what looks like an 
inverted air-bubble with its top on a level with the surface of the 
jelly, and open to the air ; along the puncture the gelatine liquefies, 
and in this may be seen the whitish mass of colonies, more par- 
ticularly at the lowest part ; in from three to four weeks liquefac- 
tion spreads to the whole mass, the bacilli falling to the bottom as 
a greyish-white sediment, having a faint orange tint in certain 
lights, and if undisturbed, a perfectly transparent liquid separates 
a whitish scum on the top from the sediment below. 
4th. A freezing temperature does not destroy it; it grows 
scarcely at all below 50°, slowly at 60°, rapidly from 80° to 100° 
Falir. in gelatine cultures. 
(For ordinary work these characters suffice for identification.) 
5th. It is actively mobile in fluid media. 
6th. Grown on agar-agar, it forms a brownish, glistening scum ; 
but this appearance is common to other organisms. 
7th. On potato slices, at a temperature of from 90° to 100° Fahr., 
it forms glistening greyish-brown colonies, but it does not grow at 
all at ordinary room temperature. 
8th. It liquefies blood serum. 
9th. Growth ceases in the absence of air in gelatine cultivation. 
10th. It is reproduced by fission. Spores have not been observed. 
Nearly all observers of this organism have described what are 
called involution forms. These are characterised by irregularities 
of shape, so that it requires re-inoculation and growth under ordi- 
nary favourable conditions to determine that the specimens having 
these appearances are indeed pure cultivations of comma bacilli. 
Ceci and others have described certain spore-like appearances in 
involution forms, but they are now regarded as dying or dead parts 
of the rods, such parts staining very slightly or not at all. 
Hueppe has described what he regards as “ lasting forms ” 
(Dauerformen), and calls “ arthrospores ” as distinguished from 
“ endospores.” These he found in cultivations which were becom- 
ing exhausted of the material for nourishment, and he examined 
only unstained specimens. If the drying test for spores is to be 
regarded as an absolute one, they are not spores. 
