Cases which have weathered one attack of appendicitis are of course by no means free from the risk of another. Indeed, at one time it was believed that a recurrence was almost certain to occur. Later investigations, based upon larger numbers of cases, now running up into the thousands, give the reassuring result that though this danger is a real one, it is not so great as it was at one time supposed, as the average number in whom a second attack occurs appears to be about twenty per cent. This, however, is a large enough risk to be worthy of serious consideration; and in view of the fact that the mortality of operations done between attacks is less than one per cent, it is generally the feeling of the profession that, where there is any appreciable soreness, or tenderness, or liability to attacks of pain in the right iliac region, in an individual who has had one attack of appendicitis, the really conservative and prudent procedure is to have the source of the trouble removed once and for all. The four principal symptoms of appendicitis are: pain, which is usually felt most keenly somewhere between the umbilicus and the right groin, though this is by no means invariable; tenderness in that same region upon pressure; rigidity of the muscles of the abdominal wall on the right side; and temperature, or fever. No matter how much and how variegated pain you may have in the abdomen, or how high your temperature may run, if you are not distinctly sore on firm pressure down in this right lower or southwest quadrant of the abdomen,--but be careful not to press too hard, it isn't safe,--you may feel fairly sure that you haven't got appendicitis. If you are, you may still not have it, but you'd better send for the doctor, to be sure. CHAPTER XIII MALARIA: THE PESTILENCE THAT WALKETH IN DARKNESS; THE GREATEST FOE OF THE PIONEER