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
The Unknown Known for Rumsfeld, Iraq. At one point, Morris asks Rumsfeld, "Have you seen "The Fog of War"? What do you think about that?" to which Rumsfeld responds, "I hate it. That man had nothing to apologize for." Morris himself has been resistant to comparisons, stating "You can’t call this ‘"The Fog of War 2".’ I can’t imagine two individuals more unalike." The Unknown Known The Unknown Known (also known as The Unknown Known: The Life and Times of Donald Rumsfeld) is a 2013 American documentary film about the political career of former U.S. Secretary of Defense and congressman Donald Rumsfeld, directed