CHATER IV. 



DISSECTION OF THE VASCULAR 

 SYSTEM. 



Injection. In dissecting the blood-vessels it will be 

 found most convenient to inject the arteries and veins 

 with different colors, using coarse injection, which will 

 not pass beyond the capillaries. The injection material 

 recommended is plaster of Paris. The dry powder 

 should be mixed with water, stirring -all the time, 

 until the liquid has the consistency of a very thin 

 faste ; the coloring matter is then added. This mix- 

 ture should not be made until it is ready to be used, 

 since it sets quickly. For the veins the best coloring 

 matter to use is a saturated aqjieous solution of 

 Prussian blue ; for the arteries, freshly prepared 

 £hrom,ate of lead held in suspension in water- To 

 prepare this latter m,ake a li solution of am- 

 m,onium, or potassium bichromate and a strong 

 solution of acetate of lead, add the latter solution to 

 the former, stirring all the while, until the bichromate 

 solution is all precipitated as yellow chromate of lead. 

 Allow the liquid to stand urdil the precipitate settles 

 to the bottom, then decant the supernatant liquid. 

 Wash the precipitate several times with water, de- 



