[Illustration: Fig. 26—Flexible Silver Canula.] Other antiseptics may be employed for the same purpose, such as bichloride of mercury (1 to 2000), or carbolic acid (1 to 80), but I much prefer the peroxide of hydrogen. The third indication (to excite a healthy action in the sinus) can be met in one of a number of ways. In the first place, before applying such remedies it will be well to obtund the sensibility of the channel by an injection into the sinus of a four-per-cent. solution of cocaine. This may be accomplished by using the same syringe and canula that are used for cleansing the fistula. If the wall of the sinus is somewhat indurated, it is better to insert a small, flexible curette (Fig. 27) and scrape the wall of the fistula along its entire length. The sinus is now prepared for some one of the various stimulating substances which have been recommended for this purpose. Among these may be mentioned peroxide of hydrogen; nitrate of silver, fused, or in solution (thirty to sixty grains to the ounce); sulphate of copper in solution (ten grains to the ounce); carbolic acid mixed with equal parts of glycerine and water. [Illustration: Fig. 27—Flexible Curette.] These substances may be applied to the fistulous track by means of cotton attached to a silver probe or to an applicator (Fig. 11, p. 26); or they may be injected into the sinus by means of the syringe and silver canula (Fig. 26, p. 57). If the fistula is a complete one and the substance used be applied as an injection, the finger should be passed into the rectum and made to cover the internal orifice of the sinus, so as to prevent the escape of any of the fluid into the bowel. Regarding the fourth point (keeping the parts at rest), the patient, whilst under treatment, should be confined to the horizontal position, either in bed or on a sofa. Congestion of the parts is thereby lessened. A firm pad placed over the anus and well supported by a T-bandage is useful in limiting the motions of the anus due to the alternate contraction and relaxation of the levator ani muscle. The chance of success in the palliative treatment of fistula in ano will be greatly increased if due attention be paid to the general state of health of the patient, and when circumstances render it possible he should be advised to seek the benefits of a change of air. ----- Footnote 46: Made by J. Elwood Lee Co., Conshohocken, Pa. CHAPTER IV. THE OPERATIVE TREATMENT OF FISTULA IN ANO. IN all cases of fistula in ano, before undertaking operative interference it is essential for the surgeon to examine the patient carefully, not only locally, but also as to the general state of health; for this disease is not infrequently complicated with other lesions—as has been previously mentioned—which may render operative procedures inadvisable.