There were, Howard Dax was aware, certain aspects of germ chemistry that defied description in terms of classical and mechanistic theory; details that seemed to require the inversion of Time's arrow. To say that a physical process was "non-reversible" usually implied the presence of the probability factor. But that didn't seem to be the case here. There was the suggestion of prophecy. Or else that time was flowing backwards. Or ... was it that something flowed backward through time? Then there was the fact that the germ plasm was immortal. Not indestructible, for the overwhelming majority of zygotes and gametes died; but if one disregarded the soma, all living germ cells had been alive since the beginning of life. After terrific work, none of which would have seemed quite orthodox to his colleagues, Dax had arrived at the end of theory and the beginning of practical application--at the taking-off point--the countdown. * * * * * Lying on the drainboard near the evaporating dish was a hypodermic syringe. If he were to dissolve the dark brown crystals and inject the solution into his veins, Dax believed that whatever it was that impeded this time-reversal would be neutralized. His consciousness--not his body, his somatic cells--would travel back along the unbroken line of his identity as a germinal continuity. Back to the extent that the effect of the chemical would allow. He would then be in the body of one of his ancestors. Not spread among them all, but following the line of greatest genetic valence to one individual: living in the Twelfth Century A. D. Probably, but not certainly, somewhere in England, since most of his ancestors came from there. Of course the time might be wrong. He had no way of making a precise determination. He had experimented with a rabbit, but after the soft little beast's eyes glazed over in unconsciousness it had immediately come to. The time taken during its visit to the purlieus of its remote and unknown forebears was of no duration in the present. And it had at once attacked him and bitten him savagely. It seemed curious that an ancestral rabbit at a period not so very far back from a biological point of view should have a spirit so foreign to the rabbits of today. Perhaps the drug had overshot its mark.... What if that were to happen in his case? Wouldn't it perhaps take him to some earlier, non-human form and then, as it were, rebound to the precise moment in history that the strength of the drug indicated? A man is not a rabbit. But suppose he found himself not in the body of a Twelfth Century Englishman--a risky enough situation--but hanging by his tail from a tree in Java? How long before the hypothetical rebound to the time of the Plantagenets? Howard Dax was too tired to concentrate on the problem: it was probably moonshine. The rabbit had been frightened, not atavistic.