Snail eggs

   The common garden snail lays about thirty eggs a year, each of them the size of a large pinhead and each one a potentíal lifesaver. The snail's egg is a cheap, readily available, and stable source of a chemical that is used to determine blood groups. Normally, thís chemical is exttacted from human blood, but it takes the blood from five donors to provide as much as is contained in a single snail's egg. The contents of the egg are extracted and dissolved in a saline solution.