Many observers have localized in the muscular system the special action of oxygen, and Spallanzani, finding that a chrysalis absorbed much less of the gas than a butterfly, argued that the difference was determined by the less movement of the former. Brown-Sequard has shown, by interesting experiments, that when the muscular and the nerve tissues have lost their vital properties, they may recover them under the influence of freshly oxygenated blood ("Journal," 1858). Thus, having injected some of his own blood (defibrinated and charged with oxygen) into the radial artery of a man executed thirteen hours previously, and whose limbs were quite rigid, muscular irritability returned to the hand. In another case he removed the arm, and three hours later, when rigor mortis was complete, he injected dog's blood through the brachial artery, and the rigidity disappeared, first in the fingers, then in other parts; the skin resumed its color, became elastic and supple, and the hair-bulbs projected (goose-flesh). In animals the vital qualities could not be restored so long after death; but, in one curious experiment, the head of a dog being cut off, was injected through the carotid and vertebral arteries, and movements of the eyes and the face-muscles continued for a quarter of an hour. Other observations have proved that oxygen augments the vital functions of the spinal cord and motor and sensory nerves, and that, by the continued injection of blood charged with it, a dead body resists decomposition for upwards of fifty hours. Richardson, injecting oxygen into the arteries of recently killed animals, tested the muscular irritability by Faradic currents, and found that the gas (warmed to 75° F.) increased irritability very much, but only for a short time. The onset of permanent rigidity was rather hastened.