A new concept is proposed of the 'perineurial vessel' as another vascular system of the body. The effects of acupuncture and moxibustion are explained as mechanical or thermal stimulation of intraperineurial cerebrospinal fluid (CSF). Fenestrated venous capillaries of circumventricular organs, including the choroid plexus, instead of arachnoid granulations, are shown to be the main site of CSF absorption. A new concept is also presented of a double circulatory system of the body, namely, in addition to the cardiovascular system, a lympho-liquid system with complete fluid circulation throughout the entire body.