The literature on experimental obstruction of the coronary arteries in animals is not extensive, although dating back to the seventeenth century, when Chirac tied the coronary artery of a dog and noted that the heart stopped beating in one minute. The next reference to this subject is Erichsen's1work in 1842, although previously to this Parry had published his observations on the relations existing between angina pectoris and sclerosis of the coronary arteries. Erichsen, recognizing obstruction of the cardiac vessels as a frequent cause of sudden death in man, ligated the coronary arteries near their origin in a pithed dog and reported gradually increasing bradycardia and finally cardiac standstill. Panum,2in 1862, attempted to obstruct the coronary arteries by injecting a mixture of oil, wax, tallow and lampblack into the aorta. As the vessels were incompletely plugged, his results are not of any special value. The next