Chapter XII: Injection of Blood and Lymph Vessels 83 



9. With a pair of fine-pointed forceps (preferably with curved 

 points) pick up one end of a thread for ligating and carefully 

 work it through under the aorta (do not mistake the vena cava 

 superior for the aorta). Tie the thread around the aorta over 

 the cannula, making a double or surgeon's knot. Draw it tightly 

 on the cannula so that the latter will be held firmly in place. 

 Run another thread through under the aorta and have it in readi- 

 ness to ligate the aorta when the cannula is withdrawn. 



10. Warm the syringe by sucking hot water into it repeatedly, 

 then fill it with warm normal salt solution. Force out a little of 

 the salt solution into the open end of the cannula, then connect 

 cannula and syringe and force the warm solution through the 

 blood vessels to cleanse them thoroughly of blood. 



11. Empty the syringe completely and rapidly fill it and the 

 cannula with the warm injecting fluid. 



12. Force out a little of the fluid from the syringe to expel all 

 air, and connect it carefully with the cannula. 



13. Force the injecting mass into the blood vessels by a slow 

 steady pressure. Begin with a very low pressure, so that the 

 large vessels will be thoroughly filled before the mass enters the 

 capillaries. The pressure should be gradually increased. Avoid 

 sudden increase of pressure or too strong pressure, for either may 

 cause a rupture of the blood vessels and consequent extravasa- 

 tion. From 8 to 10 minutes is about the time required to make 

 a good injection of the cat. 



14. Examine the intestines and the gums from time to time 

 and also the inside of the thigh (from which the skin has been 

 reflected) ; they should be deeply colored by the mass before the 

 injection is complete. If the mass begins early to flow from the 

 right ventricle, the ventricle should be ligated. In any event, it 

 is well to tie the ventricle a few minutes before completion of the 

 injection, to insure filling of all blood vessels. 



NOTE. If the gums remain uncolored, the cannula has probably 

 been forced past the arteries which lead to the head. In such a case, 

 complete the injection of the trunk and then, if injected tissue from the 

 head region is desired, cut obliquely into one side of the innominate 

 artery, tie a cannula in place and inject toward the head as in the case 

 of the aorta. 



