The Song of the Cell: An Exploration of Medicine and the New Human

by Siddhartha Mukherjee

For several decades in the late nineteenth century, the most versatile and mystifying of cells in the body was not even considered a cell. In fact, it was not visible to most microscopists: the structure of a neuron was largely hidden. In 1873, Camillo Golgi, the Italian biologist working in Pavia, found that if he added a solution of silver nitrate to a slice of translucent neuronal tissue, a chemical reaction occurred, resulting in a black stain that accumulated within some of the neurons. Under the microscope, Golgi saw a lacy network. He thought that the network represented a continuous connection—a “reticulation,” as he called it. Cell theory was itself in its infancy—Schwann and Schleiden had proposed that all organisms were collections of cells in 1838 and 1839—and so, Golgi wondered whether the entire nervous system was a spiderweb of “cellular appendages,” an “inextricable tangle” of interconnected, contiguous cellular extensions, as one writer called it. It was a mumbo-jumbo theory: as Golgi imagined it, the whole nervous system was like a fishnet, composed of wiry extensions sent out by the brain.