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 simplest type of nervous system is found in hydras and jellyfish (cnidarians) and is referred to as a nerve net.. Nerve nets do not have distinct central or peripheral regions, and lack anything that resembles a brain.Instead, the scattered nerve cells form loose networks in each cell layer of the body wall.n vertebrates, it also includes a spinal cord. The primary cell type found in the nervous system is the neuron, which has a cell body, containing the nucleus, and long extensions to carry information from one part of the body to another.