Chapter XII : Injection of Blood and Lymph Vessels 85 



from the pressure bottle by means of a Y-tube. Each must be provided 

 with a pinch-cock or clamp to hold back its contents while the other is 

 in operation. If a syringe is used, it is better to have a second syringe 

 for the second mass, although one will answer if it is rinsed out with hot 

 water before being filled with the second mass. The second mass should 

 have a quantity of very finely pulverized starch mixed with it, so that 

 when it reaches the capillaries they will become completely plugged. 



It should be borne in mind that the larger veins cannot be injected 

 in a direction contrary to their flow, because of the valves they contain. 



3. The Lungs, Liver and Kidney are readily injected through their 

 larger blood vessels with two masses, and afford very instructive material 

 when thus prepared. A triple injection of the liver may be made by 

 injecting the hepatic artery and the hepatic and portal veins. The third 

 mass may be colored with China ink. Whitman (Methods in Micro- 

 scopical Anatomy and Embryology) recommends first injecting the 

 hepatic artery and afterward the two veins. The blood should be washed 

 out of the organ to be injected with warm salt solution. 



4. To Inject Lymphatics the puncture method is commonly employed. 

 For example, an aqueous solution of Berlin blue is drawn into a hypo- 

 dermic syringe, the sharp point of the cannula is thrust into the tissue, 

 and the syringe emptied by slight, steady pressure. For practice, thrust 

 the cannula into the pad of a cat's foot, and force in some of the injection 

 mass. If the leg is rubbed upward, the fluid will flow along the lymph 

 channels and into the glands of the groin. 



5. To Keep Gelatin Injection Masses let them congeal, then cover 

 the surface with 95 per cent, alcohol, and leave in a well-stoppered vessel 

 until needed. 



6. Injection through the Femoral Artery is frequently practiced, and 

 is preferred to injection through the aorta by some workers. An 

 oblique cut is made in one side of the artery and the cannula inserted 

 pointing toward the heart. Others prefer to cut into the dorsal aorta 

 and inject both anteriorly and posteriorly. 



7. The Injecting Syringe must work without jerking or catching 

 along the wall of the barrel. It should always be carefully cleaned after 

 using. If the piston does not fit the barrel tightly enough it should be 

 wrapped with gauze. 



8. Glass Cannulae may be made by grasping the ends of a short 

 piece of soft glass tubing and heating the middle in a flame until the 

 glass becomes soft, which is indicated by the yellow color of the flame. 

 The tubing should be constantly rotated, so that all sides heat equally. 

 When the glass becomes soft, draw the tube out steadily until the 

 diameter of the soft portion becomes as small as desired. When the glass 



