I20 OPERATIVE TECHNIQUE. 



when cast. Messrs. Arnold make these instruments in many forms, all 

 fitting one handle. The head of the point or bud-firing iron consists 

 of a more or less elongated cone ; for deep firing it is drawn to a much 

 finer point. Needle firing is performed with very fine points, capable 

 of penetrating the tissues deeply. It was formerly the custom to use 

 stout needles, about four inches in length, which were brought to a 

 red heat in a charcoal furnace, grasped with pincers or forceps and 

 plunged into the tissues. These were replaced by instruments con- 

 sisting of a heavy cone-shaped head, with a central aperture through 

 which a suitable needle could be passed. The head was first heated, 

 and when red, the needle was dropped into position. In the greater 

 number of such instruments, however, the needles become cold very 

 rapidl}-, and the large head cauterises the skin around the perforation. 

 To protect the skin it becomes necessary to place a small disc of iron 

 with a central aperture over the point of operation. Several instruments 

 with movable needles have been invented. Degive's (Figs. 147 and 148) 

 is probably the best, though similar instruments have been produced by 

 Bourguet and De Place. It consists of a handle, which also acts as a 

 benzine reservoir and saturator, carrying at its extremity a small iron 

 box with a conical base, through which is drilled a hole for the passage 

 of the needle. This latter is held on a movable arm, which permits it 

 either to be extruded through the base of the box or to be retracted 

 within the latter by a spring. A bellows and benzole container supply 

 the heat, the flame playing within the cavity of the iron box. Each 

 time a puncture is to be made the red-hot needle is extruded from the 

 point of the box and thrust into the tissues. The action of the spring 

 automatically returns it to the interior of the box, where the flame 

 almost immediately renders it hot again. 



The two following firing instruments were described by the writer 

 some years ago (see ' Veterinarian,' February, 1898, p. 70). The first 

 has been used by him in his practice for nearly ten years, the second 

 for nearly four, and both have been found very satisfactory. The first 

 is Graillot's Zoo-cautery (Fig. 149). 



It is an adaptation of Paquelin's, which depends for its action on 

 the peculiar propert}^ possessed by metallic platinum, and in an even 

 higher degree by platinum in a finely divided state (platinum-black), 

 of bringing about chemical combination between oxygen and hydrogen 

 gases, or between oxygen and certain h}'drocarbon vapours, without 

 the intervention of a flame. The zoo-cautery consists, as shown 

 by the annexed rough sketch, of three principal parts, viz. the handle, 

 forming a benzoline reservoir, the stem, and the head. 



The handle (b) is formed of thin metal, spun on a lathe and 



