2. What do geologists mean when they refer to the “grains" that make
up a rock?

The scale and arrangement of the minerals or grains that make up a rock are referred to as its texture. Textures of Igneous Rock Compositions and Igneous Rock.

Explanation:

a motor homunculus represents a map of brain areas dedicated to motor processing for different anatomical divisions of the body.

homunculus represents the importance of various parts of your body as seen by your brain. as a result, they take up a lot of brain space. although the cortical homunculus is a curiosity, penfield's work in mapping the brain's relationship to the body was invaluable.