Methods Reimplantation of the left lung was carried out in eight mongrel dogs. Details of operative technic and perfusion were similar to those described elsewhere.'" 22 The pulmonaryartery was divided obliquely and recon-structed by use of a meticulous technic which approximated 1 mm. bites of vessel wall with each stitch. Four animals received 2-3 mg./Kg./day of azathioprine, 2-4 mg./Kg./day of prednisone, and rabbit anti-dog lymphocyte serum. The latter agent was given in doses of 10-20 ml./Kg. three times preoperatively and daily postoperatively for 2 weeks. The other four animals were not treated.

During the postoperative period, frontal (posteroanterior) roentgenograms of the chest were obtained daily of the unanesthetized animals in the prone position. Extensive examinations were performed on each animal on four occasions: in the early postoperative pe-riod (day 1-3), 1 week postoperatively (day 7-9), 2 weeks postoperatively (day 14-16), and 3 to 4 weeks postoperatively (day 22-31). The animals were anesthe-tized with intravenous pentobarbital and plain chest roentgenograms were obtained in the frontal (anteroposterior) and right posterior oblique (supine oblique) projections. A polyethylene catheter with side holes was then introduced into the right jugular vein and guided under fluoroscopic control into themain pulmonary ar-tery. Serial angiograms were then obtained with the animals in the right posterior oblique position, using 1.75 ml./Kg. of 60% methylglucamine diatrizoate injected at