86 THE MICROSCOPE. 



made by any tin-worker, and fitted over a gas jet to stand on ther 

 table. 



The operator should be provided with several pairs of strong for- 

 ceps, for seizing the vessel or stopping the escape of injection. 

 A small needle, fig. 67, will be found useful for passing the 

 thread round the vessel into which the injecting pipe is to 

 be inserted. Where the vessels are large, a needle commonly 

 known as an aneurism needle answers the purpose very well. 

 The thickness of thread must vary according to the size of 

 the vessel. The silk used by surgeons will be found the best 

 adapted for the purpose, and not too thin, or it may cut 

 through the vessel. 



When the size and the subject have both been properly 

 prepared, have the injection as hot as the fingers can well bear. 

 One of the pipes g, fig. 65, must then be placed in the largest 

 artery of the part, and made secure by tying. Put the stop- 

 cock f into the open end of the pipe e, and it is then ready 

 to receive the injection from successive applications to the 

 syringe a, leaving sufficient space only for the piston c. The 

 injection should be thrown in by a very steady and gentle 

 pressure on the end of the piston-rod. The resistance of the 

 vessels, when nearly full, is often considerable; but it must 

 not be overcome by violent pressure with the syringe. When 

 as much injection is passed as may be thought advisable, the 

 preparation may be left (with the stop-cock closed in the pipe) for 

 twenty-four hours, when naore material may be thrown in. 



As the method of injecting the minute capillaries with coloured 

 size is often attended with doubtful success, various other plans have 

 been proposed. Ruysch's method, according to Eigerius, was to em- 

 ploy melted tallow coloured with vermilion, to which in the summer a 

 little white wax was added. A material used by some is made of resin 

 and tallow : take of each two ounces, melted and strained through 

 linen, to which add three ounces of vermilion or finely ground indigo, 

 first well rubbed with eight ounces of turpentine varnish. Monro re- 

 commended coloured oil of turpentine for the small vessels; after the 

 use of which, he threw in the common coarse injection. 



Professor Breschet frequently employed with success milk, isin- 

 glass, the alcholic solution of gum-lac, spirit varnish, and spirit of 

 turpentine; but he highly commends the colouring matter extracted 

 from Campeachy, Pernambone, or Sandal woods. He says : " The co- 

 louring matter of Campeachy wood easily dissolves in water and in 



