88 CIRCULATION OF THE BLOOD 



Phenomena in the Circulatory System after Death. Nearly every 

 autopsy shows that after death the blood does not remain equally dis- 

 tributed in the arteries, capillaries and veins. Influenced by gravitation, 

 it accumulates in and discolors the most dependent parts of the body. 

 The arteries are always found empty, and blood accumulates in the 

 venous system and capillaries ; a fact which was observed by the ancients 

 and gave rise to the belief that the arteries were air-bearing tubes. This 

 is readily explained by the post-mortem contraction of the muscular 

 coat of the arteries. If the artery and vein of a limb are exposed in a 

 living animal and all the other vessels are tied, compression of the artery 

 does not immediately arrest the current in the vein, but the blood will 

 continue to flow until the artery is emptied (Magendie). The artery, 

 when relieved from the distending force of the heart, reacts on its con- 

 tents by virtue of its contractile coat and completely empties itself of 

 blood. An action similar to this takes place throughout the arterial 

 system after death. The vessels react on their contents and gradually 

 force the blood into and through the capillaries, which are very short, to 

 the veins, which are capacious, distensible and but slightly contractile. 

 This begins immediately after death, while the contractility of the muscu- 

 lar coat of the arteries remains, and is seconded by subsequent cadaveric 

 rigidity, which affects involuntary as well as voluntary muscular fibres. 

 Once in the venous system, the blood can not return on account of the 

 valves. Thus, after death, the blood is found in the veins and capillaries. 



