SYMPOSIUMON REGULATIONOF THE CARDIOVASCULARSYSTEMIN HEALTHAND DISEASE

both, to change the volume to a more op-timal level. Canwe fit our present knowledgeof the regulation of the red cell volume intosuch a system? Our discussion has ruled outthe outflow tap as being in anywaya precisecontroller, andhas shown that the prime reg-ulator of theinflow, M,the servomotor shown,must be the rate of division of the stem cells.