304 HOW TO WORK 



many cases the very preparations from which my drawings have 

 been made, have been preserved, and may now be compared with 

 them. 



a??. Mollification of the above Plan. Acting upon the prin- 

 ciples above referred to, I have more recently modified the foregoing 

 process by injecting the alkaline carmine fluid into the vessels in 

 the first instance for the purpose of staining the germinal matter of 

 the tissues, and afterwards, when the colouring was complete, the 

 acid Prussian blue fluid. 



The carmine fluid employed should be stronger than that already 

 recommended, p. 109, and it is better to add a little more alcohol. 

 The following succeeds well for the frog and newt. 



Carmine, 15 grains. 

 Strong liquor ammonite, -i- drachm. 

 Price's glycerine, 2 ounces. 

 Alcohol, 6 drachms. 



This fluid is to be injected carefully with very slight pressure, bear- 

 ing in mind that the alkaline ammonia is very apt to soften the deli- 

 cate vascular walls. When the vessels are fully distended, the pre- 

 paration is to be left for from twelve to twenty-four hours, in order 

 that time may be allowed for the carmine fluid which has permeated 

 the capillaries in all parts of the body to soak through the different 

 tissues and stain the germinal matter fully. Next a little pure glyce- 

 rine is to be injected, in order to cause any carmine fluid still remain- 

 ing in the vessels to pass through, or to dilute it so much that car- 

 mine will not be precipitated in quantity by the acid fluid now to be 

 introduced. 



The fine Prussian blue injecting fluid, the composition of which 

 is given on p. 296, is now to be injected with the utmost care, for the 

 vessels, particularly of young animals, having been somewhat softened 

 by the ammonia are very liable to give way if much pressure be 

 applied. When the vessels are fully distended with the Prussian blue 

 fluid, the injected preparation is to be divided into small pieces, and 

 these are to be soaked in glycerine and acetic acid, as has been 

 already recommended in p. 296. 



Very beautiful specimens from every tissue in the body of a small 

 animal (frog, newt, mouse, bat, small bird, &c.), may be prepared in 

 this way ; but as the operation of injecting has to be performed twice 

 there is greater risk of rupturing the vessels. The student should 

 therefore be an experienced injector before he attempts to carry out 

 this process, or he will meet with disappointment, and waste his in- 

 jecting fluids. 



