Tonsillectomy. Illustration of a patient having their tonsils removed using a Mathieu instrument. Tonsils are oval-shaped masses of spongy lymphoid tissue on either side of the back of the mouth. They play a role in the body's response to infection, producing antibodies for the immune system and trapping and destroying micro-organisms that enter the throat. Illustration from La Medecine Illustree, 1887.