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
Traditional Chinese medicines derived from the human body being are no more used medically, it seems rude to list them as drugs." Note the medical terms "dystocia" "A slow or difficult labor or delivery" and "stranguria" (i.e., "strangury" "A painful, frequent need to urinate, when the bladder is largely empty or with little urine production"). Reflecting the well-known Confucianist inhibition against mutilating one's body (Cooper & Sivin 1973: 212), Li Shizhen's preface to chapter 52 ethically condemns the use of some human drugs. The human is a different species from all the other organisms used as sources of drugs. In later times, Taoist alchemists [方伎之士] considered that many