INJECTION OF THE ARTERIES. 67 



not to be made, the mass may be stained by aniline of the 

 desired color." 



Excellent results have been obtained by the use of carmine 

 in coloring the mass for injecting the arteries, and Berlin blue 

 or Prussian blue for the veins. 



Kill a cat or rabbit with ether or chloroform, by putting 

 the animal into a tight box or jar with a sponge containing 

 a teaspoonful of the anesthetic. When the animal is dead, 

 open the thorax by cutting across the posterior ends of the 

 breast-bone, and through the costal cartilages on each side, be- 

 ing careful not to cut the mammary artery which runs along 

 the inside of the breast-bone on each side. The mammary 

 artery should be ligated just under the anterior end of the 

 breast-bone. Now cut away the breast-bone. The breast- 

 bone may be simply turned forward, and in this case it will 

 not be necessary to ligate the arteries. 



Find the aorta, and clear away any tissues that may obscure 

 its base. Pass a ligature under the aorta here, but do not tie 

 until the cannula is inserted. Cut a small slit in the apex 

 of the left ventricle. Have in readiness several cannulas (or 

 nozzles of a brass syringe) of 

 different sizes, made by draw- 

 ing out glass tubing. Each 

 cannula should have a distinct 

 neck, so that it may be tied in 

 firmly. Insert the cannula 

 through the ventricle into the Fig. 20. Surgeon's Knot. 



base of the aorta. Now tie 



the cannula firmly by the surgeon's knot, made by crossing 

 the two ends of the thread twice instead of once, as in the 

 ordinary knot ; draw firm with a slight sawing motion, but 

 do not tie again. (See Fig. 20.) 



For injecting, use a good brass syringe, if it can be had; a 



