The many tubes fluoresced, flared up in pulsing waves of violet and pink: there were gray bars of invisibility or areas of air in which nothing visible showed. There came the faint, crackling hum of machinery rather like a swarm of wasps in anger. Blue and gray thread of fire spat across the antenna. The odor of ozone came to Mrs. Baker's nostrils, and the acid odors burned her lungs. She was staring at him, staring at the professor's face. She half rose from her chair, and uttered a little cry. The eyes had changed, no longer were they cold, impersonal, the eyes of a man who prided himself on the fact that he kept his arteries soft and his heart hard; they were loving, soft eyes. "Allen," she cried. Yes, without doubt, the eyes of her son were looking at her out of the body of Professor Ramsey Burr. "Mother," he said gently. "Don't be alarmed. It is successful. I am here, in Professor Burr's body." "Yes," she cried, hysterically. It was too weird to believe. It seemed dim to her, unearthly. "Are you all right, darling?" she asked timidly. "Yes. I felt nothing beyond a momentary giddy spell, a bit of nausea and mental stiffness. It was strange, and I have a slight headache. However, all is well." He grinned at her, laughed with the voice which was not his, yet which she recognized as directed by her son's spirit. The laugh was cracked and unlike Allen's whole-hearted mirth, yet she smiled in sympathy. "Yes, the first part is a success," said the man. "Our egos have interchanged. Soon, our bodies will undergo the transformation, and then I must keep under cover. I dislike Burr--yet he is a great man. He has saved me. I suppose the slight headache which I feel is one bequeathed me by Burr. I hope he inherits my shivers and terrors and the neuralgia for the time being, so he will get some idea of what I have undergone." He had got down from the oscillating platform, the spirit of her son in Ramsey's body. "What--what are you doing now?" she asked. "I must carry out the rest of it myself," he said. "Burr directed me when we talked yesterday. It is more difficult when one subject is out of the laboratory, and the tubes must be checked." * * * * * He went carefully about his work, and she saw him replacing four of the tubes with others, new ones, which were ready at hand. Though it was the body of Ramsey Burr, the movements were different from the slow, precise work of the professor, and more and more, she realized that her son inhabited the shell before her. For a moment, the mother thought of attempting to dissuade her son from making the final change; was it not better thus, than to chance the disintegration of the bodies? Suppose something went wrong, and the exchange did not take place, and her son, that is, his spirit, went back to the death house?