"Herman" wrote
The picture shows the business end of an An-2. Does anybody know what
the purpose is of the objects attached to the roots of the propeller
blades?

Those are counter weights that help control the constant speed props.
Hydraulic pressure twists the blades in one direction and when removed,
the weights twist the blades in the other direction. Some props use a
large spring in the dome to accomplish the same thing.

Bob Moore
ATP CFI