THE CAPILLARY SUPPLY IN NORMAL AND HYPERTROPHIED HEARTS OF RABBITS.

1. During normal growth of the rabbit heart, muscle fibers enlarge, and the capillaries multiply so that a relatively constant capillary supply per unit of tissue is maintained from the time of birth to maturity. 2. In cardiac hypertrophy the muscle fibers enlarge, but the capillaries do not multiply and, as a result, the capillary supply per unit of tissue is reduced. 3. The decreased concentration of capillaries in the hypertrophied heart would constitute an impediment to the adequate exchange of metabolic substances, but the seriousness of the impediment cannot be estimated without further physiological data.