ACTION OF THE HEART. 63 



one of the larger pulmonary veins ; cut a hole in it near the 

 lung, and slip a glass tube into it toward the heart. This tube 

 should have a groove, made by drawing it out in the flame. 

 Another, and perhaps easier, way to keep the glass tube from 

 slipping out, is to slip over the end of the tube a piece of rub- 

 ber tube an inch or two long; but it should not project beyond 

 the end of the glass tube. If this fits snugly, it will not slip 

 on the glass tube, and the blood tubes will hold firmly when 

 tied over the rubber. It is much better to tie the tube into the 

 pulmonary vein before the vein is cut off; otherwise there will 

 be difficulty on account of the shortness of the pulmonary 

 vein. Tie the tube firmly in, and ligature the other pulmonary 

 veins without stopping to trace them. Tie all connections 

 with the heart now remaining, and cut beyond the ligatures. 

 Get a retort stand and two large glass funnels, or have made 

 a more convenient piece of apparatus (as shown in Fig. 19), 

 consisting of a sheet-iron pan eighteen inches square and two 

 inches deep, with a fixed bail handle twenty inches high, made 

 of iron rod of the size of a retort-stand rod. Attach retort 

 rings and clamps to the rod, as shown in the figure. This 

 whole apparatus, with the heart attached according to the 

 directions given, can easily be carried, and any overflow of 

 liquids will be caught by the pan. Place the funnels in the 

 rings. Lay the heart, now wholly severed from the lungs, on 

 its ventral surface. Connect one funnel by rubber and glass 

 tubing, with the left auricle by the tube already in the pul- 

 monary vein ; connect the other funnel with the right auricle, 

 through the precaval vein ; ligature the postcaval vein. Lay 

 the heart in a basin, and pour water into the funnels ; hold 

 the heart with the two hands, and compress it, repeatedly 

 adding water. In this way the clotted blood usually present 

 in the right ventricle may be washed out. If this remain, 

 it may interfere with later experiment. Connect the aorta 



