Free The Emperor of All Maladies: A Biography of Cancer by Siddhartha Mukherjee Page A

experiment demolished vitalism. Organic and inorganic chemicals, he proved, were interchangeable. Biology was chemistry: perhaps even a human body was no different from a bag of busily reacting chemicals—a beaker with arms, legs, eyes, brain, and soul.
    With vitalism dead, the extension of this logic to medicine was inevitable. If the chemicals of life could be synthesized in a laboratory, could they work on living systems? If biology and chemistry were so interchangeable, could a molecule concocted in a flask affect the inner workings of a biological organism?
    Wöhler was a physician himself, and with his students and collaborators he tried to backpedal from the chemical world into the medical one. But his synthetic molecules were still much too simple—mere stick figures of chemistry where vastly more complex molecules were needed to intervene on living cells.
    But such multifaceted chemicals already existed: the laboratories of the dye factories of Frankfurt were full of them. To build his interdisciplinary bridge between biology and chemistry, Wöhler only needed to take a short day-trip from his laboratory in Göttingen to the labs of Frankfurt. But neither Wöhler nor his students could make that last connection. The vast panel of molecules sitting idly on the shelves of the German textile chemists, the precursors of a revolution in medicine, may as well have been a continent away.

    It took a full fifty years after Wöhler’s urea experiment for the products of the dye industry to finally make physical contact with living cells. In 1878, in Leipzig, a twenty-four-year-old medical student, Paul Ehrlich, hunting for a thesis project, proposed using cloth dyes—aniline and its colored derivatives—to stain animal tissues. At best, Ehrlich hoped that the dyes might stain the tissues to make microscopy easier. But to his astonishment, the dyes were far from indiscriminate darkening agents. Aniline derivatives stained only parts of the cell, silhouetting certain structures and leaving others untouched. The dyes seemed able to discriminate among chemicals hidden inside cells—binding some and sparing others.
    This molecular specificity, encapsulated so vividly in that reaction between a dye and a cell, began to haunt Ehrlich. In 1882, working with Robert Koch , he discovered yet another novel chemical stain, this time for mycobacteria, the organisms that Koch had discovered as the cause of tuberculosis. A few years later, Ehrlich found that certain toxins, injected into animals, could generate “antitoxins,” which bound and inactivated poisons with extraordinary specificity (these antitoxins would later be identified as antibodies). He purified a potent serum against diphtheria toxin from the blood of horses, then moved to the Institute for Sera Research and Serum Testing in Steglitz to prepare this serum in gallon buckets, and then to Frankfurt to set up his own laboratory.
    But the more widely Ehrlich explored the biological world, the more he spiraled back to his original idea. The biological universe was full of molecules picking out their partners like clever locks designed to fit a key: toxins clinging inseparably to antitoxins, dyes that highlighted only particular parts of cells, chemical stains that could nimbly pick out one class of germs from a mixture of microbes. If biology was an elaborate mix-and-match game of chemicals, Ehrlich reasoned, what if some chemicalcould discriminate bacterial cells from animal cells—and kill the former without touching the host?
    Returning from a conference late one evening, in the cramped compartment of a night train from Berlin to Frankfurt, Ehrlich animatedly described his idea to two fellow scientists, “ It has occurred to me that . . . it should be possible to find artificial substances which are really and specifically curative for certain diseases, not merely palliatives acting favorably on one or another symptom. . . . Such curative substances—
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