The tonsils are lymph nodes at the base of the tongue. Unfortunately they are so near the surface of the throat that they frequently become infected from the throat itself, and so become the seats of pus pockets, as already noted. Closely related to the tonsils are the masses of adenoid tissue at the back of the throat which frequently grow to an undue size in children, and are then known as adenoids. The harm done by adenoids is chiefly mechanical; they may block the Eustachian tubes, and so cause deafness, as already mentioned in Chapter IX, or they may interfere with the free movement of the air through the nasal passages. Children in whom this condition exists are mouth breathers. Adenoids, like tonsils, are subject to infection, and so may give trouble by becoming the sites of poison formation. Adenoids represent always an overgrowth and for that reason may be removed without any possibility of hampering the proper working of the body. Experience has shown that children whose development appears to be hindered by the presence of adenoids are almost invariably benefited by having them removed. The tonsils are normal parts of the bodily structure and as such undoubtedly have a regular work to do, but here again experience has shown that harm from persistent pus pockets is so much greater than harm from loss of function following their removal as to justify taking them out, whenever pus pockets develop in them. There are enough lymph nodes in the region about the throat, so that if tonsils or adenoids are removed any foreign matters that get into the body fluids will still be filtered out.
One more function of the lymph nodes must be mentioned; this is their property in preventing the spread of cancer cells. We now know that so-called secondary cancers are the result of the spread of cancer cells from the original seat of the cancer to other parts of the body, and that this spread is much hindered by the ability of the lymph nodes to catch the cancer cells and hold them. Unfortunately sooner or later some of the cells will escape beyond the lymph nodes and so spread the malignant growth throughout the body, but until this happens the cancer is confined to the region where it started, and it is during this period that complete cure by surgical means is possible. It is because of the imminent danger of the escape of cancer cells beyond the restraining lymph nodes that relief by surgery should be sought at the very earliest possible moment. Delay, whether due to carelessness or any other cause, is as certainly fatal in the case of cancer as in any other disease for which a cure is known.