As he looked, the translucence faded and his skin switched to normal, the marks disappearing. That was the word, switched. He ought to be thankful for that, he supposed. Somehow he wasn't. He was out of the autobath and half dressed before the realization came to him. He knew what the network was, the patterned marks beneath his skin. A circuit. A printed circuit, or, since it was imposed on flesh, possibly tattooed. [Illustration] A circuit. What did anyone use a circuit for? To compute, to gather data, to broadcast, to control. How much of that applied to him, to the body it was concealed in? The first he could eliminate. Not to compute. As for the rest, he was not certain. It seemed possible that everything could be included in the function of the network beneath his skin. He hadn't been controlled up to now, but that didn't mean control wasn't there, quiescent, waiting for the proper time. However, it didn't seem likely. Human mentality was strong, and a reasonably intact mind was difficult to take over. What else? To gather data and broadcast it. Of that he could be almost positive. The data came from his nervous system. He suspected where it was broadcast to--back to the police. How the circuit on his body gathered data was unknown. The markings appeared to parallel his central nervous system. It seemed reasonable that it operated by induction. That meant it involved chiefly tactile sensations, unless, of course, there were other factors he didn't know about. He felt his forehead carefully, his temples, and his skull around his ears. Nothing, but that didn't mean that infinitesimal holes hadn't been drilled through his skull and taps run to the optic and auditory nerves. It could be done and he wouldn't know about it, couldn't feel it. The broadcasting circuits could then be spread over his head, or, for that matter, over any part of his body. If his suppositions were correct, then he was a living, walking broadcasting station. Everything he felt, saw or heard was relayed to some central mechanism which could interpret the signals. The police. Cobber had been looking for a spy mechanism, a mechanical device in Jadiver's body. He hadn't found it, but it was there, almost impossible to locate. A surgeon might find it by performing an autopsy, but even then he would have to know what to look for. How Jadiver had been able to find it was a pure puzzle. Obviously, the police hadn't been as thorough as they had meant to be. Their mechanism had somehow gone awry at precisely the time Jadiver was most conscious of his skin. Without the itch, he would never have noticed it. At least one thing was clear now--the purpose. He'd been boiled into unconsciousness, his skin removed, the circuit put in place, and then had the synthetic substance carefully fitted over his body.