It was a wonderful relief when the solitary journey was over and the elderly disguise laid aside. "Shall I ever feel really young again?" said the girl, who was not quite twenty-four. But not for a moment did she doubt that there was work waiting for her in the big, unexplored world.

During those early days in Paris, Marie often had reason to be grateful for the plain living of her childhood that had made her independent of creature comforts. Now she knew actual want in her cold garret, furnished only with a cot and chair, like a hermit's cell. She lived, too, on hermit's fare—black bread and milk. But even when it was so cold that the milk was frozen,—cold comfort, indeed!—the fire of her enthusiasm knew no chill. Day after day she walked from laboratory to laboratory begging to be given a chance as assistant, but always with the same result. It was man's work; why did she not look for a place in a milliner's shop?

One day she renewed her appeal to Professor Lippman in the Sorbonne research laboratories. Something in the still, pale face and deep-set, earnest eyes caught the attention of the busy man. Perhaps this strange, determined girl was starving! And besides, the crucibles and test-tubes were truly in sad need of attention. Grudgingly he bade her clean the various accessories and care for the furnace. Her deftness and skill in handling the materials, and a practical suggestion that proved of value in an important experiment, attracted the favorable notice of the professor. He realized that the slight girl with the foreign look and accent, whom he had taken in out of an impulse of pity, was likely to become one of his most valuable helpers.

A new day dawned for the ambitious young woman. While supporting herself by her laboratory work, she completed in two years the university course for a degree in mathematics, and, two years later, she won a second degree in physics and chemistry. In the meantime her enthusiasm for science and her undaunted courage in the face of difficulties and discouragements attracted the admiration of a fellow-worker, Pierre Curie, one of the most promising of the younger professors.

"I love you, and we both love the same things," he said one day. "Would it not be happier to live and work together than alone?"

And so began that wonderful partnership of two great scientists, whose hard work and heroic struggle, crowned at last by brilliant success, has been an inspiration to earnest workers the world over.

Madame Curie set up a little laboratory in their apartment, and toiled over her experiments at all hours. Her baby daughter was often bathed and dressed in this workroom among the test-tubes and the interesting fumes of advanced research.

"Irene is as happy in the atmosphere of science as her mother was," said Madame Curie to one of her husband's brother-professors who seemed surprised to find a crowing infant in a laboratory. "And if I could afford the best possible nurse, she could not take my place! For my baby and I know the joy of living and growing together with those we love."

What was the problem that the mother was working over even while she sewed for her little girl, or rocked her to sleep to the gentle crooning of an old Polish folk-song whose melody Chopin has wrought into one of his tenderest nocturnes?