Stung

I suffered my first sting of the season today while I was hacking down nettles in the garden, which offers a tenuous excuse to celebrate the achievements of Robert Hooke FRS, the father of English microscopy. Hooke was born in Freshwater on the Isle of Wight in 1635 and in a varied career, that included research in mechanics, astronomy and architecture, produced perhaps the most celebrated book on microscopy: Micrographica, or Some Philosophical Descriptions of Minute Bodies made by Magnifying Glasses withe Obervations and Inquiries thereupon. Samual Pepys bought a copy and commented ‘took home Hook’s book of microscopy, a most excellent piece’, as well he might, as some of Hooke’s descriptions and detailed, exquisite engravings would not be out of place in a biology text book today. Compare his engraving of the stinging hairs on a nettle leaf , above, with the photograph of the hairs on the leaf of the nettle that stung me today – astonishingly accurate, when you consider the rudimentary nature of the microcope lenses he was working with nearly four centuries ago. The nettle sting is a remarkable structure – a long, tapered hollow cell on a pediment (or a 'bladder' as Hooke called it), filled with irritants under pressure and tipped with a minute hooked glass bead that snaps off at the slightest touch, turning the hair into a hypodermic syringe. After watching the whole processes of stinging himself under his microscope, Hooke recorded the following:”The chief thing therefore is, how this plant comes, by so light a touch, to create so great a pain; and the reason of this seems to be nothing else, but the corrosive penetrant liquor contain’d in the little bags or bladders, upon which grow out those sharp syringe-pipes......”. All of Hooke's wonderful engravings from Micrographia can be viewed at http://archive.nlm.nih.gov/proj/ttp/hooke_home.html