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 majority of the nervous system is tissue made up of two classes of cells: neurons and neuroglia. 1  Neurons. Neurons, also known as nerve cells, communicate within the body by transmitting electrochemical signals. 2  Afferent neurons.