form. There exist right crystals and left crystals similar to one another as the right hand is to the left, but which can not be laid over one another; the direction of the deviation of polarized light corresponds with the direction of the crystalline form. It must be supposed that, after the solution of a right or left body, its separated molecules are still dissymmetrical. Of like character are the separate steps of a winding stairway; their form tells whether the stairs turned to the right or the left. Now, all superior organic bodies—the albumens, the sugars, dextrin, and cellulose—are what we call active bodies, endowed with the power of turning the plane of polarized light to the right or the left; and never by any artifice of the laboratory has it been possible to prepare directly a right body or a left body. In spite of the synthesis of alcohol urea, and formic acid, we still have a right to say organic matter is not fabricated outside of the living being. The work of life can not be counterfeited. We can not artificially provoke the formation of a cell; we can no more reproduce the materials of which it is made. The substances we have been able to reproduce are only the waste of life returning toward inert matter, and already nearly mineral."
The analysis of these few pages can be summarized by saying that the synthesis of all the products of life, without exception, was long regarded as a contradiction to the laws of mineral matter and as an impossibility. Yet chemistry has performed the synthesis of some products of life—urea, formic acid, ethylic alcohol, etc. But the authors of the challenge do not acknowledge themselves beaten; they have simply drawn back and circumscribed the field of their defeat. "Yes," they say, "we acknowledge that chemistry has been able to perform the synthesis of some products of life; but they are inferior products, refuse. It has still been never able to prepare directly the superior products like albumen and the sugars. We can not counterfeit the work of life."
The reader has been able to view and measure the motion of retreat. We can, with a little kindliness, regard it as having been performed in good order. But we can also, with entire impartiality, see in it the first steps of a backward march which will end in a rout. We can indeed say that the rout has already begun. In fact, the reputed impassable has just been partly passed, and syntheses characterized as impossible have been in large part realized.
The synthesis of the most important of the series of sugars is now an accomplished fact. The researches which have permitted the realization of this immense advance in organic chemistry, and which are the work of M. Fischer and his pupils, have led to a discovery of great importance. In the series of sugars we met