146 ANATOMICAL TECBNOLOGY. 



into it, so that no air may get into the syTing&. Connect the syr- 

 inge with the canula which is in the vess^ (§■ 358). Hold the cannla 

 firmly with one hand and pull toward the syringe as the mass is 

 forced into the vessel. Be sure that the vessel is^not looped or 

 twisted in the least, but drawn peripherad jiist enough to straighten 

 it. Force the piston down steadily and continuously ; do not allow 

 it to stop until the injection is finished. If the canula becomes 

 clogged, the resistance will be complete, and there will be an 

 entire absence of the elastic feeling which comes from the distended 

 arteries. Very often the canula may be opened by pulling the pis- 

 ton back a little and then forcing it down quickly. 



One can tell only by experience when the injection is finished. 

 The vessels are usually filled, however, when the piston returns 

 slightly on remitting the pressure. If the injection is carried too 

 far or the pressure is too great, the semilunar valves (Fig. 102) are 

 liable to be ruptured and the heart filled, or some vessel may give 

 way. 



§ 360. Tying the Vessel. — As soon as the injection is finished, 

 tie the vessel with the thread provided for the purpose (Fig. 42), 

 draw back the piston slightly, and then cut the string holding the 

 canula in the vessel and remove the canula. 



§ 361. Cleaning the Canula, Syringe and Mixing Dish. — Do 

 this immediately after the injection is finished before the plaster has 

 time to set. Expel the plaster remaining in the syringe into the 

 waste pail ; then fill the syringe with water and empty it. Do this 

 several times, and then force some clean water through the canula. 

 Finally, it is best to unscrew the top of the syringe and pour out 

 any liquid that has passed the piston. 



Throw any plaster remaining in the mixing dish into the waste 

 pail and clean out the dish very thoroughly. The plaster must not 

 be thrown into the sink lest it should set and clog the waste pipe. 

 The dissection may commence in half an hour after the injection is 

 finished. 



§ 862. Injection of the Femoral Vein — ^Fig. 39. — Dissect the 

 vein free for 2 or 3 cm. from the abdominal wall as described for 

 the artery (§ 353). Compress the vein and force the blood centrad. 

 It will pass vQYj readily and leave the vein nearly empty. Now 

 press on the vein just as it enters the abdomen and try to force the 

 blood periplierad. There will be seen a bulging in the vessel ex- 

 tending about .5 cm. from the body wall. There are two valves at 



