96 HOW TO WORK 



182. Dr. Carter's Carmine Injecting Fluid. For a carmine in- 

 jecting fluid which will run perfectly freely through the most minute 

 capillaries, and one that will not tint the tissues beyond the vessels 

 themselves, Dr. Carter has found the following formula to answer 

 satisfactorily: 



Pure carmine 60 grains. 



Liq. ammon. fort. (P. B.) ... ... 120 



Glacial acetic acid 86 minims. 



Solution of gelatin (i to 6 water) 2 ounces. 



Water i| 



The carmine is to be dissolved in the solution of ammonia and 

 filtered, if necessary. With this mix thoroughly an ounce and a half 

 of the hot solution of gelatine. The remaining half ounce of gelatin 

 is to be mixed with the acetic acid, and dropped, little by little, into 

 the solution of carmine, stirring briskly during the whole time. 

 (Archives of Medicine, vol. Ill, p. 287). 



This fluid is admirably adapted for specimens which are to be 

 mounted in Canada balsam, but not for those to be preserved in 

 glycerine. The vessels are well displayed, but all the delicate nerve 

 fibres are invisible. 



Transparent injecting fluids of several different colours are very 

 much to be desired, but although many experiments have been made in 

 the hope of obtaining such, we are, as yet, restricted to two, the blue 

 and the red. Thiersch has succeeded in making others, the com- 

 position of one of which, yellow, is given below. I have not myself 

 met with much success hitherto in the use of these fluids, for if I 

 employ them according to the directions given, I am unable to 

 demonstrate the masses of germinal matter (nuclei), and various 

 points of importance ; and when made according to the principles 

 followed in the case of the Prussian blue fluid, the results are by no 

 means satisfactory, and as the colour is, in many cases, affected by 

 acids, the subsequent steps of my process are interfered with. See 

 part V. They may, however, be useful to those who prefer to follow 

 out other plans of investigation. 



An injecting fluid of a greenish tint may be made, according to 

 the directions given in page 94, for Turnbull's blue, by employing 

 different proportions of the ingredients, i grain or less of the 

 sulphate of iron to 10 grains of the ferridcyanide of potassium. 



Thiersch (Das Mikroskop, 1865, von Dr. H. Frey) prepares a 

 transparent yellow injecting fluid as follows : 



