The brain is a spongy organ made up of nerve and supportive tissues. It is protected by the skull. The base, or lower part of th
e brain is connected to the spinal cord at the brain stem. Together, the brain and spinal cord are known as the central nervous
system (CNS). The spinal cord contains nerves that send information to and from the brain. The cerebrum is the largest part of
the brain and is divided into two parts called the left and right cerebral hemispheres. The two hemispheres are connected by the
corpus callosum. The outer surface of the cerebrum is called the cerebral cortex or grey matter, and he inner area of the
cerebrum is referred to as the white matter.
You would find the greatest variety of species in the tropics, and coral reefs. The Amazon basin in South America has the largest area of tropical forests where you could find the most variety of species.
You can't see the blood vessels themselves because vision depends on a process that makes it impossible to see things that are stationary with respect to the retina. Light receptors in the retina respond only to changes in light reaching them, not to a steady image.
