Gerlach and others had some luck using carmine to highlight different kinds of cell structures, but where Gerlach got stuck was in exploring the tissues of the brain.
Back in his day, a few scientists had been tinkering with staining tissues, especially with a compound called carmine — a red dye derived from the scales of a crushed-up insects.
So one day, he tried making a diluted version of the stain — thinning out the carmine with ammonia and gelatin — and wetted a sample of brain tissue with it.
By its carmined lip, its near-smart hat, its babbling of " him, " and by the knowledge which looks boldly out of its eyes you know it is tragically old.