Hypodermic syringes are used to inject substances into or extract liquids from the body. They consist of very think, hollow needle attached to a syringe. Christopher wren was the first to experiment with hypodermic needles in the 17th century, using animal bladders as the syringe and goose quills as the needle. It was impossible to perform injections without an incision until after the invention of the hollow needle by Irish Physician Francis Rynd in 1844.