=Operator, Assistants, Nurses.=--Usually one assistant, who stands opposite the operator, and two nurses, are sufficient. A second assistant, standing beside the operator, is useful to thread needles and to hand instruments and ligatures. The operator, assistants, and nurses should possess such general cleanliness as follows a morning bath. They should not attend any patients suffering with a septic or infectious condition upon the day of the operation. If they have done so upon the previous day, they should subsequently take a general bath and change all clothing. Care in this respect is especially desirable on the part of the nurses, whose long hair prevents easy cleansing of the head. [Illustration: FIG. 194.--View of the sterilizing and operating rooms of the Gynecean Hospital, Philadelphia. The apparatus is arranged for operation. _A_, flasks of sterile water; _B_, jar containing silk ligatures in glass tubes; _C_, instrument-sterilizer containing boiling water; _D_, tray containing sterile water for instruments at operation; _E_, basin for washing sponges; _F_, basin for washing hands of operator during operation; _G_, tray for sutures, ligatures, and needles; _H_, jar of cold sterile water; _J_, kettle of hot sterile water; _K_, water-sterilizer; _L_, dressing-sterilizer.] The operator and assistants should wear sterilized outer clothes--cotton shirt and duck trousers. A large sterilized apron put on immediately before the operation is an additional protection. The nurses should wear large sterilized aprons over freshly washed, if not sterilized, dresses. The hands and forearms of the operator, assistants, and nurses should be bare and especially sterilized. The finger-nails should be short, rounded, and smooth. A long nail is difficult to clean, and in the case of the operator is dangerous, as it may lacerate important structures in the process of enucleation of a tumor. Enucleation of adherent growths is best done with the blunt finger, which passes along the planes of separation. The sharp nail may perforate an intestine or lacerate a blood-vessel, instead of pushing it aside. The nails, fingers, hands, forearms, and lower part of the upper arms should be thoroughly scrubbed with frequently changed hot water and soap (preferably soft soap) and a large stiff nail-brush. The process should not be done hastily or but once. The soap should be repeatedly washed off and renewed. Five minutes, at least, should be devoted to the scrubbing. The hands and arms should then be similarly scrubbed with alcohol, and finally scrubbed with a solution of bichloride of mercury 1:1000. Immediately before proceeding with the operation the hands and arms should be rinsed in sterile water. There should be a nail-brush for each solution used. The brushes should be clean and sterilized by boiling or by placing in the steam sterilizer.