AURICULAR CANAL, the tube leading from the external ear to the ear drum. It is about tin. long and is lined by thin skin which is tightly bound to the cartilage and bone on which it rests. The outer one-third is formed by cartilage; the inner two-thirds by bone. The few short crisp hairs at the entrance of the canal serve as a barrier to dust and small insects. In the skin of the outer portion are glands which secrete a sticky yellow material called cerumen, or wax. This also serves to catch small particles. The cerumen sometimes becomes packed in, causing sudden deaf ness, and should then be removed by a physician. The short, straight, constricted tube, connecting the auricular with the ven tricular portions of the embryonic heart is also known as the auricular canal.