=Indications for Drainage.=--Great diversity of practice exists among operators as to the use of drainage after celiotomy, and a decided change has taken place in regard to drainage during the past twenty years. In the early days of modern abdominal surgery drainage was used very much more than it is at present; some of the best operators used it in the majority of their cases; now a number of operators never use drainage after celiotomy, while others use it only when specially indicated. Much depends upon the individual methods of the operator. The operator who is careless in his asepsis and hemostasis should use drainage oftener than he who is careful in these particulars. The advice, “When in doubt drain,” is very good; but the surgeon should strive to eliminate the element of doubt as much as possible, and to have a definite reason for all his procedures. If drainage is not necessary, it is harmful. It necessitates more frequent dressings and disturbance of the patient, and it prevents perfect closure of the abdominal incision. The object of drainage is the removal from the peritoneum of discharges which are, or which may become, septic or dangerous. Such discharges are blood, pus, serum, cyst-contents, and ascitic fluid. Even though the peritoneum be dry and all bleeding be arrested when the operation is completed, yet it must be remembered that a subsequent free serous exudation will take place if the peritoneum has been exposed or subjected to chemical or mechanical irritation. Infection may take place from imperfect asepsis at the time of operation; or it may be caused by the escape into the peritoneum of septic material which existed in the abdomen before the operation; or it may occur subsequently, from the passage of septic organisms from the interior of the intestine through the intestinal wall. The absorbing power of the healthy peritoneum is so great that a large amount of fluid (even though not absolutely sterile) may be taken up by it. Injury of the peritoneum from exposure or other irritation not only increases the amount of fluid to be absorbed, but it diminishes the power of absorption; and injury of the intestinal peritoneum or of the wall of the intestine favors the passage of septic organisms through it. The operator should bear these facts in mind when he considers the subject of drainage. A certain amount of absorption of blood or other sterile fluid may be trusted to the peritoneum.