Aluminium versus aluminum. Following up a Topical Words piece on the international spelling of what British English writes as sulphur, many American subscribers wrote in to ask about another element with two spellings: aluminium.
The simplest and presumably most primitive form of nervous system is termed a nerve net. In a nerve net, neurons are dispersed in a thin layer, not clustered into nerves or a central nervous system (CNS), and they are positioned seemingly at random relative to each other.he simplest and presumably most primitive form of nervous system is termed a nerve net. In a nerve net, neurons are dispersed in a thin layer, not clustered into nerves or a central nervous system (CNS), and they are positioned seemingly at random relative to each other.
The nervous system is divided into two major parts: the central nervous system and the peripheral nervous system. The central nervous system, the largest part of the nervous system, consists of the brain and the spinal cord. The peripheral nervous system consists of the cranial nerves, spinal nerves, and the autonomic (automatic) nervous system.