David says: “This is the radula of a common marine rocky shore “netted dog whelk” Nassarius reticulatus photographed at 200x magnification. Snails feed by scraping off food (algae growing on rocks, or your lettuce in the garden) with a long ribbon-like “tongue” or radula. The Radula is a funny structure – it’s like a conveyor belt – the teeth are on it and as it gets worn out it grows another behind.”
2 Peacock feather
David says: “This is a feather of a male peacock or Indian peafowl, Pavo cristatus. This is taken at the edge of the blue eyespot on one of the tail feathers at 100x magnification. The light interferes with the layers of the feather and so you get colours being produced much like those of an oil slick on the surface of water.”
David says: “The front surface of the eye is covered by a clear transparent structure called the cornea – all the light for seeing travels through this clear surface eye structure. Yet it is not as transparent as you might think – for one thing it is covered in nerve cells for sensing when the eye is touched (remember how painful a bit of sand in your eye is!). Normally transparent, the nerve cells in the picture, which is taken from a Victorian slide, have been stained with silver to make them visible, shown here at 400x magnification.
David says: “The pale white parchment-like outer skin covering garlic cloves are remarkable in having their cells filled with beautiful crystals of oxalic acid! This acid (calcium oxylate) is used by the plant for protection against animals that might want to eat it (like the snail). In plants these crystals are known as raphides and it is the same chemical that forms kidney stones in Humans! Here the crystals are made visible by polarised light at 200x magnification.