In the Graduate Schools

The discovery of a hitherto unknown adrenalin-like hormone was announced yesterday at New Haven in a paper read before the Yale Medical Society by Dr. W. B. Cannon '96, George Higginson Professor of Physiology at the Harvard Medical School. Dr. Cannon who spoke on "The Explanation of a Mysterious Emotional Increase in the Heart Rate," revealed that a chemical substance, which he has named "sympathin" is given off by smooth muscle when stimulated by nerves attached to the spinal cord, over which the brain has no control, and affects the heart directly as does adrenalin. It has previously been supposed that adrenalin and allied substances were given off by the adrenal glands. This discovery is termed by scientists an important forward step in elucidating the action of the sympathetic nervous system and the emotional acceleration of the heart.

Experimented on Cat

Professor Cannon described his conclusive experiment. Using a cat, he severed all nerves connected with the heart, as well as all nerves connected with every organ which produces known hormones. He also cut the upper spinal cord transversely. The only nerves left intact were a few strands running from the spinal cord to the smooth muscle of the lower abdominal region. He then caused the fore part of the animal to struggle, and observed no change in the heart rate. After causing the hind part of the animal to struggle, however, he noticed a slow increase in the heart rate. Since the only connection left between the heart and the lower part of the animal was the blood stream, he deduced that something in the blood was affecting the heart. Accordingly, he interrupted the blood flow going into and from the lower abdominal region and immediately observed that the acceleration of the heart was repressed, and after releasing the blood flow, the increase in the heart rate was resumed.

"Since the only tissue known to be affected by sympathetic stimulation in this region is smooth muscle," Dr. Cannon explained, "and since the only connection between the hind part of the animal is the blood stream, and since interfering with the stream in the region where smooth muscle is stimulated either markedly depresses or abolishes the response, the inferences are drawn that a substance is given off from smooth muscle into the blood, that it is carried effectively by the blood to distant organs, and that it influences those organs in a favorable manner, i.e., as sympathetic impulses would influence them."