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FINE INJECTION. 



For the purpose of examining microscopically the finer arteries 

 and veins and the capillaries in a tissue, and their relation to the 

 other parts, it is necessary to fill them with some colored injection 

 mass, or otherwise stain or color them. Numerous injection masses 

 are in use; the following meet the general needs. For injection 

 fluids for special purposes, consult the literature [6]. 



216. Carmine gelatin mass. Formula: Dry gelatin, 75 

 grams; carmine (No. 40), 10 grams; water, 90 c. c.; ammonia, 10 

 c. c.; acetic acid, q. s.\ chloral hydrate, 10 grams. 



Soak the gelatin in water until it is soft; pour off the superflu- 

 ous water and melt it (in an agate or porcelain dish) over a water 

 bath. Grind the carmine to a paste with water; add all the am- 

 monia and water; filter, warm to 80 or 90 C., and add to the warm 

 gelatin. Then add slowly the acetic acid diluted with an equal vol- 

 ume of water, while constantly stirring the mass, until the mass 

 smells very slightly of the acid. Filter through fine flannel. If the 

 mass is acid, the chloral hydrate may be safely added (as a preserva- 

 tive) ; if any ammonia is present it will decompose it forming chloro- 

 form, and a granular precipitate. If too much acid is added, the 

 gelatin will not set. 



217. Berlin blue injection mass. Formula: Dry gelatin, 

 75 grams; saturated aqueous solution of Berlin blue, 150 c. c.; chloral 

 hydrate, 10 grams. Prepare the gelatin in the manner given above 

 ( 216); warm the Berlin blue solution (to 80 or 90 C.), and add 

 it to the hot gelatin. Heat the mixture for 10 minutes or more, 

 stirring it occasionally, and filter it through fine flannel and add the 

 chloral hydrate. 



218. For securing the best results in injecting the following 

 conditions should be observed: (1) A young but nearly mature, 

 lean animal is to be preferred. (2) Kill the animal with an anes- 

 thetic (chloroform) and leave it in the anesthetic at least half an 

 hour before beginning the injection; do not, however, wait until 

 rigor mortis sets in. (3) Inject only the part desired, tying all an- 

 astomosing vessels and all vessels to other parts. Inject into the 

 artery of the part, leaving the vein open until nearly pure injection 

 mass escapes, then tie it and continue the injection until the part 

 feels hard and is the color of the injection mass. (4) When the 

 injection is finished cool the part injected by means of cold water, 

 ice, or snow. 



