DISEASES AND ENEMIES. 
553 
redness, to sterilise it. It immediately cools, when we, 
having first passed the end of the cotton plug through 
the flame, to burn off any germs resting upon it, hold 
our tube to be inoculated mouth downwards, touch 
the needle upon the diseased material, withdraw the 
plug, and carry the needle upwards through the 
gelatine; the bacteria upon the former are left behind, 
the plug is immediately re-inserted, and in a few days 
colonies of bacteria will be observed growing in the 
needle track. With Bacillus alvei^ Mr. Watson Cheyne 
and myself found a most extraordinary arrangement 
of the colonies, which has marked off this bacillus as 
not only new to science, but one of quite peculiar 
interest. The colonies, after four or five days’ growth, 
are seen as little, whitish, opalescent, globular masses, 
each containing, probably, many million individuals ; 
but the bacilli soon break off from these, apparently 
in search of nutriment, and, liquefying the gelatine 
they touch, form fluid tracks, through which they swim, 
and establish at length sub-colonies at a distance. 
While many bacilli resemble alvei individually, the 
colony form is characteristic, and distinguishes it from 
every other. The progress made during twentv-four 
hours may be judged by drawings of a single tube, as 
seen at noon on two consecutive days (A and B, 
Fig. 122). If these bacilli are growing on a flat surface, 
their behaviour is almost fantastic. An actual form, 
from a sketch, is given at G. As the nutriment con- 
tained in the medium becomes exhausted, the bacilli, 
as in the body of the bee, begin to pass into the rest 
or spore condition, showing the forms a, b, c, d, E. 
Some of the spores from the first tube, being now 
