"I was able to pursue my studies in Paris. I had taken a quiet lodging in one of the smaller streets of the Marais, and I passed a great deal of my time at the hospital, where I devoted my days to the study of anatomy, while my evenings were mostly spent in the laboratory of an old man with whom I had studied toxicology forty years before. He had been one of the experts in the Brinvilliers case, and perhaps knew more about the secret poisoners of Paris than any living man. My life under such circumstances was full of interest and occupation; but I never let a day pass without paying a visit to the street where Mr. Topsparkle had his apartment. This was also in the Marais, and not ten minutes' walk from my own obscure lodging. "I heard the sounds of music and gaiety from those lighted windows night after night, saw visitors enter, saw Margharita pass to her carriage or her sedan-chair, saw all the indications of a life devoted to pleasure and dissipation. One night I followed the chair to the Opera House, and took my seat in the pit, from which I saw my granddaughter in her box, blazing with diamonds, and one of the loveliest women in the house. My neighbours pointed her out to each other, and talked of her as the rich Englishman's mistress. "'Is she not his wife?' I asked. My neighbour shrugged his shoulders, and answered as a true Parisian cynic: "'Wife or mistress is all the same nowadays, except that in some cases the mistress is the more virtuous. Every fine gentleman's wife is some other fine gentleman's mistress; but I believe there is here and there a Miss who is faithful to her protector.' "This kind of life continued for a little more than four months, and then one morning I found Mr. Topsparkle's splendour melted like a fairy palace and the apartment in the Marais to let. He had gone to London with all his retinue, including Fétis, whom I had met several times in the street and who had tried to make his peace with me. I had, however, treated all his advances with contempt, and on but one occasion did I stoop to speak to him. This was to accuse him of having carried Margharita away under the influence of the Indian drug, the knowledge of which he had obtained in my laboratory. "'Do you think drugs were needed?' he asked sneeringly. 'You have seen the lady. If she is a snared bird, you will admit that she is uncommonly fond of her cage.' "I followed the seducer to London, and found myself a cheap lodging in an alley near St. Martin's Lane, from which den I went forth daily and nightly to keep watch upon my granddaughter's life.