AND HOW TO USE IT. 175 



Sternal ribs of both sides sufficiently far from the middle line not 

 to injure the mammary arteries, cutting across the posterior end of 

 the sternum and turning it forwards. Slit open the pericardium, 

 and make a large incision, by a single cut of the scissors, in each 

 ventricle. All this should be done rapidly (if possible, before the 

 heart has ceased to beat), as it is desirable to get rid of as much 

 blood as possiblci Pass a ligature round the aorta close to its 

 exit from the heart, and give it a single loose tie. When the 

 bleeding has ceased, sponge the blood from the heart, and pick 

 out any clots which may have formed in the left ventricle, pass a 

 cannula through the incision in the left ventricle into the aorta, 

 tighten the ligature, and knot it firmly. By this operation, the 

 whole of the systemic arteries are injected. The pulmonary 

 arteries may be filled by proceeding similarly on the right side. 

 The postal vein is readily injected from its branch to the caudate 

 lobe, the cannula being directed towards the main trunk. The 

 injection of the systemic veins is more difficult. The precavals 

 may be filled from the external jugular, the post-caval from exter- 

 nal iliac, the cannula in both cases being directed towards the 

 heart. For anatomical purposes, injection with plaster is the best. 



Injecting a Frog.— Kill with chloroform. Introduce one blade 

 of the scissors carefully beneath the sternum, and cut it through 

 the median line. Slit open the pericardium and the fleshy part of 

 the heart, seized with forceps. Cut an opening into the ventricle. 

 Do not wait long for the blood to escape, but wash it away with 

 the wash-bottle as it appears. Introduce the filled pipe of the 

 syringe, and secure firmly in place by passing the thread around 

 the heart-substance and back over the pin on the nozzle. Just the 

 end of the pipe should be included, for if it is thrust too far, 

 there is great danger of the point passing through the delicate 

 coats of the vessel. 



Injecting Eye of Ox. —The pipe is inserted in the artery close 

 to the nerve. Two or three minutes will be time enough to make 

 a complete injection. If the globe becomes very much distended 

 by the fluid, an opening must be made in the cornea to allow the 

 humours of the eye to escape. Thus space is left for the injection, 

 and the vessels may be completely distended. 



