1st. The appliance for continuous instillation should never be connected up with several tubes, nor with a tube perforated with several holes. As the output of a drop-counter is very small, all the liquid should flow through a single tube and emerge from a single hole in this tube, the hole and the tube being dependent on gravitation. Consequently, instillation drop by drop should only be used for wounds which contain a single tube, perforated at its extremity (Fig. 45), or a single tube sheathed with "tissu eponge" (bath-towelling).

2nd. The apparatus for intermittent instillation can be connected up with four tubes perforated with tiny holes, or even, in certain cases, with eight. As the yield of the irrigating tube is considerable, the liquid, at the moment when the spring of the pinch-cock is released, spurts out from all the holes of all the tubes. As much as possible, tubes of a length of 5 and of 10 cm. should be used, especially if a single flask furnishes the liquid to eight tubes.

It will not do to serve from the same cannula both simply-perforated tubes and tubes sheathed in "tissu eponge." By reason of the different resistances, the liquid would escape almost entirely by the simply perforated tubes.

It is important to remember this difference in the action of the two forms of apparatus, for continued instillation and for intermittent instillation, because, if a drop-counting appliance be used in connection with a system of general perforated tubes, no result will be obtained. The device for intermittent instillation is used much more frequently than the apparatus for continued instillation, because it allows a single irrigation reservoir to provide liquid for four or eight tubes at once (Fig. 46). It is therefore applicable to all large wounds.

Fig. 45.   Apparatus arranged for drop by drop instillation: a, Reservoir; b, Irrigation tube; c, Screw pinch cock; d, Drop counter; e. Distributing tube (Fig. 38, A); f, Conducting tube with terminal orifice (Fig. 36).

Fig. 45. - Apparatus arranged for drop-by-drop instillation: a, Reservoir; b, Irrigation tube; c, Screw pinch-cock; d, Drop-counter; e. Distributing tube (Fig. 38, A); f, Conducting tube with terminal orifice (Fig. 36).

Fig. 46.   Apparatus for intermittent instillation: a, Reservoir {ampoule or flask holding a litre); b, Irrigating tube with a diameter of 7 mm.; c, Pinch cock (Pince de Mohr); d, Distributing tube with 4 branches; e, Conducting tubes.

Fig. 46. - Apparatus for intermittent instillation: a, Reservoir {ampoule or flask holding a litre); b, Irrigating tube with a diameter of 7 mm.; c, Pinch-cock (Pince de Mohr); d, Distributing tube with 4 branches; e, Conducting tubes.