Signaling as precisely as the neurons in our brains do, to make sense of the world. I scribbled quick calculations based on our isotope work. It occurred to me that the amount of carbon transferred relative to nitrogen was strikingly similar to their respective quantities in molecules of an amino acid called glutamate. We hadn’t exactly sought in our experiments to trace glutamate’s carbon-nitrogen movements, but other researchers had verified that the amino acid itself did move through mycorrhizal networks. I
