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
History of beliefs about the human body about what he proposed as the discovery of the clitoris, stated that, "like a penis, "if you touch it, you will find it rendered a little harder and oblong to such a degree that it shows itself as a sort of male member." (There was much debate on the actual discovery of the clitoris between male European scientists and many claimed to have described it first: by dissecting the human body and writing down what was observed these European scientists could claim in their idea of the body that they had discovered or created new knowledge.) This one-sex model was