If you resection the lower spinal cord of a cat such that the nerves to the hind legs are isolated from the brain, and the cat is still able to walk on a treadmill, you have demonstrated that motor commands must have originated in the lower portion of the spinal cord. This is evidence for the existence of .

Central pattern generators

Explanation:

A central pattern generator (CPG) is a neuronal circuit consisting of neurons localized in the spinal cord capable of producing rhythmic outputs. CPGs are able to produce rhythmic movements even when the spinal cord is separated from the brain and sensory organs. CPGs are the main components of motor functions including, among others, breathing, flying, chewing, walking, swimming, etc. These neural circuits have been discovered in almost all vertebrates studied to date.

prophase: we can observe the chromosomes to coil up and condense. they become visible. nuclear membrane and envelope disintigrate.s

metaphase: chromosomes align at the center, the metaphase plate. spindle fibers attach to centromeres of the sister chromatids. they meet at kinetochores.

anaphase: sister chromatids are pulled towards each opposing centromere, set on different poles.

telophase: chromosomes are now clustered up only on either sides of the cell. nuclear membranes reform, and a new cell wall forms along the cell plate. this will lead to cytokinesis, the process that divides the cell membrane and forms the cell wall.