Gr. S. GrRAHAM-SMITH 
23 
Deep colonies. 
Iu each group the deep colonies differ to a greater or less extent 
from the superficial colonies, and the deep colonies produced by the 
organisms belonging to the four groups differ from each other in their 
appearance and mode of production as greatly as do the superficial 
colonies. Nevertheless the mode of division, the method of post- 
fission movement and the function of the capsule remain the same in 
each group whether growth is occurring in the depth or on the surface, 
and the differences in the deep colonies can be attributed in each case 
to the same variations in the strength and behaviour of the capsule, 
which influence the superficial growths. 
Detailed account of observations. 
Group I. The “ loop forming ” group. 
The only organism belonging to this group which was studied was 
B. anthracis. 
During the early stages of growth the original organism increases in 
length and divides, producing a chain of closely connected rods, which 
develops a distinct curve near its centre. This primary curve soon 
develops into a loop, and secondary loops are rapidly produced at the 
opposite side of the chain. To accommodate the rapidly increasing length 
of the chain further loops are produced, and the pressure they exert 
results in the compression of the central portions of the primary, 
secondary and later loops to such a degree that for long distances their 
walls are in apposition. Thus long wavy strands of parallel chains of 
bacilli are produced. Ultimately therefore the colony is composed of 
a central portion consisting of numerous wavy strands of parallel chains 
of bacilli running in various directions, and of a peripheral portion 
formed by the numerous loops in which the strands terminate. The 
terminal portions of the original thread can generally also be recognised 
as delicate wavy processes projecting from the colony, and often showing 
systems of loops like those seen in the earlier stages of growth of the 
primary colony. 
Diagram 1 is reproduced from a series of drawings made during 
the development of a superficial colony from a single anthrax bacillus. 
Over each figure the time in minutes from the commencement of the 
observation is given. 
