I n 1919, Krogh did the first work on the quantitative study of capillaries in skeletal muscle. With an ocular micrometer, he studied cross-sections of muscle injected with India-inkgelatin and made capillary counts for two muscles of the frog, two of the guinea-pig, one of the cod, one of the dog, and one of the horse. I n 1925, Stoel made a similar study for one red and one white muscle of the rabbit. On the basis of results from two muscles, he suggested a ratio of 2: 1 for abundance of capillary supply in the red and white varieties of muscle. Further work was done on rabbit muscle by Duyff and Bouman in 1927. They reported counts on fourteen muscles, but their figures do not substantiate Stoel's suggested ratio.
METHOD
The present work was done on homologous muscles of the rat, guinea-pig, and cat. Capillary counts per unit crosssectional area of muscle were made. I n addition, the following values were computed f o r each muscle: first, the proportion of muscle tissue t o connective tissue in the muscle fasciculi ; secondly, the average cross-sectional area of muscle tissue which is metabolically dependent on a single capillary ; and thirdly, the average area of transverse sections of muscle fibers. Animals were etherized, and by cannulation of the iliac artery and Capillary counts were made on injected muscle.