Prevention of Splenic Fever, &c., at the Brown Institution. 279 
clear space appears in the middle between the two highly refractile 
segments. This clear space does not as yet indicate a complete 
separation, for a delicate outline can be seen uniting the two 
rods, which . later become entirely separate. This outline is 
the delicate sheath which surrounds the rods, but is not readily 
seen during the simple rod stage. 
When the organism is cultivated in the manner already 
described, changes occur which usually follow a certain course. 
Similar changes may also take place in the carcass of the dead 
animal, especially if the temperature is favourable. 
The short rod elongates rapidly into a long filament, com- 
posed of a homogeneous protoplasm enclosed in a very delicate 
hyaline sheath, and this filament may grow to a great length, 
curving in all directions and forming loops or spirals. These 
long filaments are often united in parallel bundles, or cross 
obliquely in a very characteristic manner. 
As this elongation proceeds, changes take place within the 
substance of the rod which may assume one of two forms. The 
more common is as follows : The central protoplasmic mass of 
the rod becomes somewhat granular in appearance, and the 
protoplasm appears broken at certain points, clear specks, as 
seen in the lower straight rod of 2, Fig. 1, sometimes appearing 
at regular intervals. Then the protoplasm shrinks, leaving clear 
spaces, with ovoid or oblong highly refractile bodies arranged 
at regular intervals, as at 3, Fig. 2, or more irregularly or in 
pairs, as at 4, Fig. 2, and 7, Fig. 3. These oblong or ovoid 
bodies are the now well-known spores. 
Fig. 2. — Stages of Bacillus anthracis under Cultivation. 
I. Wavy filament, showing commencing lateral formation of spores, aa granular dots. 2. Another 
part of same cultivation, filament dividing, each segment having a terminal dot. 3. Filament in 
which spores have formed at nearly regular intervals. 4. Portions of filament with spores after 
division. 5. Isolated spores. 6. Sporules formed by division of spores. 
One of two things may happen : the spores may remain in 
situ in the remains of the filament, which persists only as an 
almost invisible shred of the external hyaline capsule, or they 
