"Foreign influences like viruses may disrupt this order and cause cancer. The cells are continually in a state of change, but always replace their characteristic molecules, and it is only as they grow older that they gradually become 'worn out.' Then the body grows old, becomes less resistant to infection, and eventually succumbs to one disease or another. And you know, of course, that viruses also have this self-duplicating ability.
"I reasoned that at birth a man had a definite, finite amount of this essential self-duplicating entity—SDE—in his body cells, a kind of directing factor which reproduces itself, but more slowly than do the body cells. In that case, with the normal multiplication of the cells, the amount of SDE per cell would slowly but surely grow smaller with the years. Eventually the time would come when the percentage would be below the critical level—the cells would be less resistant, would function with less efficiency, and the man would 'grow old.'"
Karl nodded soberly. "Reasonable hypothesis."
"But one day, by pure chance, I isolated a component which I recognized as being the factor essential to the normal functioning of body cells. It hit me like a toothache. I found that I could synthesize the SDE in the lab, and the only problem then was to get it into a man's cells. If I could do that, keep the SDE level up to that of youth, a man would stop aging! Since viruses penetrate our cells when they infect us, it was no trick at all to effect a chemical coupling of the SDE to the virus. I used Martian Blue, since it was handy, and its effects are usually brief.
"Presto! Old age is held at bay for another twenty or thirty years—I really don't know how long. These mice were my first experiment, and as you see, they're still alive. Next, I tried it on myself."
David put the mice back in their cage, locked it, and returned to the lab.
"Tomorrow, the whole thing is bound to come out because Tanya Hachovnik is coming back. You know her sister Leah—gray, dried-up, soured on life. Well, I've had ways of checking, and when Tanya Hachovnik walks into the Institute, everyone will see her as the same luscious redhead of twenty-five we knew ten years ago. I realize that what I did was a criminal act. I didn't think the thing through or I wouldn't have been such a fool. But when I made those final experiments, I used the Hachovnik twins for a controlled pair."
"You must have been crazy!"
"Perhaps I was. I'd tried it on myself, of course, with no bad effects except a few days' fever, but I realized that without a control I never could be sure the SDE was actually working. It might be just that my particular genetic constitution caused me to age more slowly than the average. So I chose the twins. To Leah I gave the attenuated Martian Blue, but to Tanya I gave the simple Blue coupled with SDE. The experiment worked. Identical twins—one grows old like other people; the other remains young. I know now, Karl, how to prolong youth indefinitely. But what in the name of Leader Marley shall I do with my knowledge?"
Karl Haslam absently twisted his white hair and spoke slowly, as though he found trouble in choosing his words.