44 THE MICROSCOPE 



carmine injections is to precipitate the carmine, and so prevent it 

 from transuding through the walls of the vessels into which it is 

 thrown. 



Asphalt and Chloroform.— Ludwig has recently employed a 

 mass, consisting of asphalt dissolved in chloroform and filtered, 

 for the injection of the bile ducts. The merit of this fluid is, 

 that chloroform, being an extremely mobile fluid, flows readily 

 along the vessels, and that it rapidly evaporates and leaves them 

 filled with a solid black mass. 



Berlin Blue. — One or two per cent, solution is especially good 

 for cold-blooded animals, and also for blood-vessels, and bile-ducts ; 

 in using the two per cent, solution for the ducts warm it first, as it 

 is then less likely to excite contraction of the biliary ducts. 



Alcannin and Turpentine. — A solution of alcannin, or alkanet 

 in turpentine, or in chloroform, is used for injecting the lym- 

 phatics. The solution is of a bright red colour. Both the 

 turpentine and the chloroform solutions flow readily. When the 

 latter is employed, the chloroform evaporates and leaves the 

 alcannin in the vessels. (Ludwig.) 



Nitrate of Silver for blood-vessels. — If a frog be taken, kiU it 

 by stunning it on the head ; expose the heart, strip off its apex, 

 and allow it to bleed thoroughly. Push a glass or brass canula 

 from the ventricle into one of the aortse, and inject a stream of 

 distilled water to wash out the blood with its chlorides ; inject 

 one-quarter per cent, silver nitrate solution, allow to remain for 

 eight or ten minutes, and then wash it out with distilled water. 

 The most convenient parts to take are the mesentery and bladder. 

 If desirable to silver also the epithelium covering the mesentery ; 

 this is done after injection. In the case of a warm-blooded 

 animal, such as a guinea-pig, the water and the silver solution are 

 both heated to 39*^ C. The fluids are injected into the aorta. A 

 solution of nitrate of silver may also be injected into the 

 lymphatic gland, areolar tissue, testis, lung, etc., for the fixing and 

 staining of tissue elements. 



MuUer's Prussian Blue.— Cold flowing blue mixture, made by 

 the precipitation of soluble Prussian blue from a concentrated 



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