Answer:
Cyanobacteria are microscopic organisms found in all kinds of water. They are single-celled organisms and produce their own food from sunlight via photosynthesis. Cyanobacteria are important to evolution because they developed the oxygen atmosphere we live in by producing waste from cyanobacteria. Plants also evolved from Cyanobacteria.
Cell Size, Presence of other cells, and Chemical Stimulators
The answer is Walter Hess
Hess manipulated the diancephalon of the brain of cats by inserting metal rods in the hypothalamus regions of the brain, where the diencephalon is located, and passing electrical current through the rods to the brain region. He noticed that the cats, among other complex behavioral changes, would curl up and sleep.