1. Adrenalin causes a marked constriction of the human coronary artery, although it undoubtedly produces a relaxation in some mammals; e. g., calf, sheep, pig, etc.

2. The human coronary artery is probably provided with sympathetic vasoconstrictors.

3. If human blood-vessels are obtained in a warm condition within a few hours after death, they are often suitable for biological and pharmacological study.