Breathing is useless without the proper minimum of red corpuscles in the blood. People below that minimum die of asphyxiation although their lungs are full of pure air. The red corpuscle count was falling too fast. The time she and Max had to work in was too short. "Pump some more CO_{2} into the air system," Max said urgently over the phone. "Get some into the men's end of the ward." * * * * * She looked through the microscope at the live sample of blood. It was a dark clear field and bright moving things spun and swirled through it, but she could see nothing that did not belong there. "Hal," Max called over the general speaker system, "cut the other treatments, check for accelerating anemia. Treat it like monoxide poisoning--CO_{2} and oxygen." She reached into a cupboard under the work table, located two cylinders of oxygen, cracked the valves and handed one to Max and one to the assistant. Some of the bluish tint left the assistant's face as he breathed and he went over to the patient with reawakened concern. "Not breathing, Doc!" Max was working at the desk, muttering equations of hemoglobin catalysis. "Len's gone, Doc," the assistant said more loudly. "Artificial respiration and get him into a regeneration tank," said June, not moving from the microscope. "Hurry! Hal will show you how. The oxidation and mechanical heart action in the tank will keep him going. Put anyone in a tank who seems to be dying. Get some women to help you. Give them Hal's instructions." The tanks were ordinarily used to suspend animation in a nutrient bath during the regrowth of any diseased organ. It could preserve life in an almost totally destroyed body during the usual disintegration and regrowth treatments for cancer and old age, and it could encourage healing as destruction continued ... but they could not prevent ultimate death as long as the disease was not conquered. The drop of blood in June's microscope was a great, dark field, and in the foreground, brought to gargantuan solidity by the stereo effect, drifted neat saucer shapes of red blood cells. They turned end for end, floating by the humped misty mass of a leucocyte which was crawling on the cover glass. There were not enough red corpuscles, and she felt that they grew fewer as she watched. She fixed her eye on one, not blinking in fear that she would miss what might happen. It was a tidy red button, and it spun as it drifted, the current moving it aside in a curve as it passed by the leucocyte. Then, abruptly, the cell vanished. June stared numbly at the place where it had been. Behind her, Max was calling over the speaker system again: "Dr. Stark speaking. Any technician who knows anything about the life tanks, start bringing more out of storage and set them up. Emergency." "We may need forty-seven," June said quietly.