3. _Locked-jaw_ is a disease in which there are spasms and a contraction of the muscles, usually beginning in the lower jaw. It is serious, often fatal, yet it sometimes follows as trivial an injury as the stroke of a whip lash, the lodgment of a bone in the throat, a fishhook in the finger, or a tack in the sole of the foot. 4. _Gout_ is characterized by an acute pain located chiefly in the small joints of the foot, especially those of the great toe, which become swollen and extremely sensitive. It is generally accompanied by an excess of uric acid in the blood, and a deposit of urate of soda about the affected joint. Gout is often the result of high living, and of too much animal food. It is frequently inherited. 5. _Rheumatism_ affects mainly the connective, white, fibrous tissue of the larger joints. While gout is the punishment of the rich who live luxuriously, rheumatism afflicts alike the poor and the rich. There are two common forms of rheumatism--the inflammatory or acute, and the chronic. The latter is of long continuance; the former terminates more speedily. The acute form is probably a disease of the blood, which carries with it some poisonous matter that is deposited where the fibrous tissue is most abundant. The disease flies capriciously from one joint to another, and the pain caused by even the slightest motion deprives the sufferer of the use of the disabled part and its muscles. Its chief danger lies in the possibility of its affecting the vital organs. Chronic rheumatism--the result of repeated attacks of the acute--leads to great suffering, and oftentimes to disorganization of the joints and an interference with the movements of the heart. 6. _Lumbago_ is an inflammation of the lumbar muscles and fascia. [Footnote: Lumbago is really a form of myalgia, a disease which, has its seat in the muscles, and may thus affect any part of the body. Doubtless much of what is commonly called "liver" or "kidney complaint" is only, in one case, myalgia of the chest or abdominal walls near the liver, or, in the other, of the back and loins near the kidneys. Chronic liver disease is comparatively rare in the Northern States, and pain in the side is not a prominent symptom; while certain diseases of the kidneys, which are as surely fatal as pulmonary consumption, are not attended by pain in the back opposite these organs.--WEY.] It may be so moderate as to produce only a "lame back," or so severe as to disable, as in the case of what is popularly termed a "crick in the back." Strong swimmers who sometimes drown without apparent cause are supposed to be seized in this way.