Chris finished treating the family with impersonal efficiency, discussing the symptoms loudly with Harkness. "It's a good thing it isn't serious!"
"No," Harkness answered bitterly. "Not serious. It's only killed five children and three adults so far!"
"It would, here," Doc agreed unhappily. He led Chris out of the room on the pretext of washing his hands. "It's serious enough to force us to abandon the whole idea of going back to Earth-normal. Measles today, smallpox, tuberculosis, scarlet fever and everything else tomorrow. These people have lived Mars-normal so long their natural immunity has been destroyed. On Earth where the disease was everywhere, kids used to pick up some immunity with constant exposure, even without what might be called a case of the disease. Here, the blood has no reason to build antibodies. They can be killed by things people used to laugh at. How the disease got here, I don't know. But it's here. So we'll have to give up the idea of switching back to Earth-normal."
He gathered up one of the kits and started toward the other houses. "And Lord knows how long it will take to get the blood for the other treatment, even if it works."
They worked as a team for a while, with Harkness frowning as he watched Chris. Finally the young doctor stopped Chris outside the fifth house. "These are my patients, Dr. Ryan. I left the Lobby because I didn't believe colonials were mere livestock. I still feel the same. I appreciate your help in diagnosis and methods of treatment. But I can't let you handle my patients this way."
"Dan!" She swung around with eyes glazing. "Dan, are you going to stand for that?"
"I think you'd better wait in the tractor, Chris."
He was lucky enough to catch the kit she threw at him before its precious contents spilled. But it wasn't luck that guided his hand to the back of her skirt hard enough to leave it stinging.
Her face froze and she stormed out. A moment later they heard the tractor start off.
But Doc had no time to think of her. He and Harkness split up and began covering the streets, house by house, while he passed on the word to abandon the metabolism switch and go back to Mars-normal.