Trachea Diffusion of oxygen and carbon dioxide takes place across the walls of the smallest tubes, called tracheoles, which penetrate tissues and even indent individual cells. Gas may be conducted through the respiratory system by means of active ventilation or passive diffusion. Unlike vertebrates, insects do not generally carry oxygen in their haemolymph. This is one of the factors that may limit their size. A tracheal tube may contain ridge-like circumferential rings of taenidia in various geometries such as loops or helices. Taenidia provide strength and flexibility to the trachea. In the head, thorax, or abdomen, tracheae may also be connected
Heather (given name) Heather (given name) Heather is a common English speaking nation given name, for girls. The name Heather actually refers to a variety of small shrubs with pink or white flowers which commonly grow in rocky areas that is literally referred to as Heather, in English. The brush is native to Scotland and England, but it is more commonly found in Scotland due to its rocky territories. The name is derived from Middle English "hather". Heather has several other definitions. The most commonly known is as a reference to a color mixture, it is most often a pale shade of blue