Persons occasionally suffered acute distress from gumboils or had attacks of sore throat owing to the infected condition of the tonsils, but beyond these no particular attention was paid to the pus-forming organisms, unless, as occasionally happened, an especially virulent type became established which brought on the condition commonly known as blood poisoning. Within the last few years the discovery has been made that there is a steady discharge of poison from every pus pocket into the body fluids and so to the blood stream. The amount is ordinarily so small that the body as a whole is not seriously affected, but now and then, either because of a larger production of poison or because of a lower resistance on the part of the body, serious ill effects are produced. Among them may be mentioned acute (inflammatory) rheumatism. This is not only an extremely painful condition, but it is very likely to leave serious after-effects, as, for example, injured heart valves, to give trouble for the rest of life. The discovery of these facts has given us great respect for pus pockets, so we no longer treat them carelessly. Infected tonsils are looked after, not simply because they bring about sore throat now and then, but even more because of the poison which they are likely to send through the body. It is probably not too much to say that the practice of dentistry has been revolutionized since the significance of pus pockets has been discovered. Formerly the killing of nerves to relieve aching teeth or to insure them against future aching was a common practice. The modern dentist, on the other hand, kills nerves to teeth with the very greatest reluctance and only as a last resort, because he knows full well that in so doing he is opening the way for the establishment of pus pockets with the train of ills that is likely to follow. At the present time methods of curing pus pockets at the base of the teeth are not very adequate, so that the extraction of the tooth has to be resorted to, but there is every reason to believe that the dental profession will shortly find methods by which pus pockets can be controlled without having to sacrifice the teeth.