26 
PRINCIPLES OF BACTERIOLOGY 
the endoplasm; they are called Ernst-Babes’ or metachro- 
matic (from Greek meaning changing color) grannies; 
nothing definite is known as to their significance. 
Capsules.—Quite a few bacteria are surrounded by an 
envelope or a halo which is called “capsule” (from Latin 
capsula, meaning a little box) ; the capsules are most fre¬ 
quently present in the organisms (e. g., pneumococcus) 
when they are first isolated from animal tissues or if 
Fig. 2.—Pneumococci, showing capsules. (Mallory and Wright —Pathological 
Technic .) 
grown on substances rich in albuminous ingredients, and 
frequently lose these if grown on ordinary substance. As 
to the significance of the capsule, the most accepted opin¬ 
ion is that the capsule renders the bacteria more resistant 
against destruction and thereby more dangerous (virulent, 
from Latin vis, meaning power) ; the statement that pneu¬ 
mococcus has an especially well defined capsule when 
freshly isolated from animal tissues and is apt to lose it 
