Methods for Injecting. 



When it is desired to bring out prominently the rela- 

 tion between tiie blood vessels and the other elements of a 

 tissue or an organ, it is necessiuy to inject the vessel. 

 This is best done by means of substances which are fluid 

 when warm, Init harden on cooling. Gelatin, which has 

 been colored with some dye, is usually employed. The 

 directions for making two such injecting masses are here 

 given. Much experience is required to inject successfully; 

 too much space would be required to go fully into the 

 methods used. They are demonstrated in the coarse on 

 metJiods. 



Carmine Gelatin (Gerlacli). 



The formula is taken from Behren's Tabellen. 



Carmine 



Ammonium hydrate 

 Water 



Gelatin 

 Water 



10 grms.) 

 1 c. c. [ I. 



8 c. c. ) 



12 grms.^ ^j 

 16 c. c. S ^^' 



The gelatin is cut into fine pieces, placed in an evapo- 

 rating dish, and. tke water added ; in tliia tha pieces soiik. 

 about 12 hours. The gelatin is then dissolved over a 

 water-bath. To solution II, add solution I (which is ]>re- 

 pared by dissolving the carmine in the ammonium hydrate 

 and w'ater over a water-bath), slowl}', while constantly stir- 

 ring. The mass is now alkaline, and unless neutralized 

 would stain the ])lood vessels and surrounding tissue. The 

 neutralization is accomplished ])y means of glacial acetic 

 acid, which is added drop by drop until no ammonia is de- 

 tected by the sense of smell, stirring well after every drop. 



