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 

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

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

 since it sets quickly. For the veins the best coloring 

 matter to use is a saturated aqzieous sohition of 

 Prussian blue ; for the arteries, freshly prepared 

 chromate of lead held in suspension in water. To 

 prepare this latter make a ifo solution of am- 

 mo7iiiim 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 ycllozu chromate of lead. 

 Allow the liq2cid to stand until the precipitate settles 

 to the bottoin, then decant the supernatant liquid. 

 Wash the precipitate several times with water, de- 



