The Golgi Stain, circa 1873

Museo di Storia dell’Università di Pavia

More than three decades after the German biologists Theodore Schwann and Matthias Schleiden first proposed that the cell was the basic functional unit of all living things, in 1838, many of the world’s leading histologists still disagreed about the fine structure of the nervous system. Some maintained that the brain was also made of cells, while others argued that it consisted of a continuous network of tissue, or “reticulum,” formed by the fused processes of nerve cells.

In 1873, the Italian physician Camillo Golgi described a staining technique that helped resolve the issue. Golgi set up a makeshift laboratory in the kitchen of the small-town hospital near Milan where he worked, and spent his evenings preparing brain slices for imaging. Under the glow of candlelight, he discovered that by first hardening a sample of nervous tissue in potassium bichromate and ammonia, then immersing it in a silver nitrate solution, he could clearly visualize silhouettes of the neuronal cell body, axon, and dendrites (as shown here in an illustration of a stained hippocampus drawn by Golgi in 1883). Other investigators, most notably the neuroanatomist Santiago Ramon y Cajal, adopted the method—dubbed the Golgi stain—and exploited advances in microscopy to reveal nerve cells in increasingly greater detail. Eventually, by the 1890s, most researchers accepted that the nervous system was composed of individual and discrete cells, though Golgi, who discovered the organelle named in his honor in 1898, clung to the reticulum theory throughout the rest of his life.

Golgi and Cajal were awarded the Nobel Prize in 1906—the first time that the Prize was shared between two Laureates. In the English translation of his autobiography, Cajal wrote: “The other half [of the Prize] was very justly adjudicated to the illustrious professor of Pavia, Camillo Golgi, the originator of the method with which I accomplished my most striking discoveries.”