METHODS OF INJECTING THE BLOOD-VESSELS. 31 



simpler to inject both arteries and veins with the same solution. 

 If a small animal is to be employed (as the rabbit, for instance) 

 it will be found most convenient to inject through the aorta. 

 If, however, an organ from the human body is to be injected, 

 through the main vessels of that part. To commence with, the 

 kidney is probably the best, as it is small and of firm consis- 

 tence. 



For injecting with the red gelatine liquid the following rules 

 will be found of service, and yield good results : 



Take 40 grammes of Cox's best English gelatine, place it 

 in a jar, and add just water enough to cover it ; let it stand 

 for several hours, when it will imbibe the water, being hygro- 

 scopic ; it may then be dissolved over a water-bath. 



Take of the carmine 22 grammes and dissolve in 40 c.c. of 

 aqua ammonite, then add 240 c.c. distilled water, and filter. 

 The preparation of the carmine solution had better be com- 

 menced the day before, as it takes about twenty-four hours to 

 filter. The gelatine and carmine solutions are raised, separately, 

 to the same temperature, when the gelatine solution is gradu- 

 ally added to the carmine solution, under constant stirring. 

 The injection fluid, which is now of a deep cherry-red color and 

 alkaline reaction, is precipitated with acetic acid until the deep 

 cherry color gives place to a bright red, and the ammoniacal 

 odor is exchanged for that of acetic acid. At this point a little 

 more acid may be added without doing harm. In case the 

 liquid should be found too concentrated, a little more water 

 may be added. For the blue mass the following method may 

 be adopted : 



Take 66 grammes of gelatine, and prepare as in the former 

 case. Add 4 grammes of soluble Berlin blue in substance and 

 360 c.c. of water. 



The blue will also be found slow in filtering. When both 

 are heated to the same temperature add the gelatine to the 

 blue solution, with constant stirring. When this has been 

 done, a solution of the iron salts may be added to intensify the 

 blue color, care being exercised not to add enough of the iron 

 to coagulate the gelatine. This liquid also may be diluted 

 if found so concentrated that it will not flow easily. The 

 liquids having been prepared, the organ carefully removed 

 from the body, thoroughly washed out and heated to a tem- 

 perature of 98 F., everything is ready for injection. The fill- 



