These, then, are what the arteries draw into themselves on every side; those arteries which reach the skin draw in the outer air[390] (this being near them and one of the lightest of things); as to the other arteries, those which pass up from the heart into the neck, and that which lies along the spine, as also such arteries as are near these--draw mostly from the heart itself; and those which are further from the heart and skin necessarily draw the lightest part of the blood out of the veins. So also the traction exercised by the diastole of the arteries which go to the stomach and intestines takes place at the expense of the heart itself and the numerous veins in its neighbourhood; for these arteries cannot get anything worth speaking of from the thick heavy nutriment contained in the intestines and stomach,[391] since they first become filled with lighter elements. For if you let down a tube into a vessel full of water and sand, and suck the air out of the tube with your mouth, the sand cannot come up to you before the water, for in accordance with the principle of the refilling of a vacuum the lighter matter is always the first to succeed to the evacuation. XIV Alla mên kai hôs en hekastê tôn artêriôn esti tis dynamis ek tês kardias epirrheousa, kath' hên diastellontai te kai systellontai, dedeiktai di' heterôn. Eiper oun syntheiês amphô to te tautên einai tên kinêsin autais to te pan to diastellomenon helkein ek tôn plêsion eis heauto, thaumaston ouden soi phaneitai tas artêrias, hosai men eis to derma perainousin autôn, epispasthai ton exôthen aera diastellomenas, hosai de kata ti pros tas || phlebas anestomôntai, to leptotaton 205 en autais kai atmôdestaton epispasthai tou haimatos, hosai d' engys tês kardias eisin, ex autês ekeinês poieisthai tên holkên. en gar tê pros to kenoumenon akolouthia to kouphotaton te kai leptotaton hepetai prôton tou baryterou te kai pachyterou; kouphotaton d' esti kai leptotaton hapantôn tôn kata to sôma prôton men to pneuma, deuteron d' ho atmos, epi toutô de triton, hoson an akribôs ê kateirgasmenon te kai leleptysmenon haima.