A DETERMINATION OF THE CIRCULATION RATE IN MAN AT REST AND AT WORK

Bornsteinf in 1910 introduced the principle of measuring the volume of blood per minute passing through the lungs of man by calculating, from the tension difference existing between the gas (nitrogen) in the alveolar air and in the blood, the quantity absorbed by the blood from the lungs in a known time. The next year Markoff, Muller, and Zuntz2 improved the method by using nitrous oxide instead of nitrogen. Krogh and Lindhards in 1912 nearly coincidently with Markoff, Muller, and Zuntz employed nitrous oxide and developed the method to a high degree of accuracy. Krogh* has recently shown, however, that an error of the order of about 6 per cent exists in all the blood flow experiments given in the above paper, as well as in recent papers by Lindhard,s because in the calcula-