In this series of experiments the theoretical optimum conditions were fulfilled, i. e., very rapid auto-grafts were made and the use of salt or other foreign solution avoided. A segment of common carotid artery interposed between the ends of a divided common carotid artery for twenty-eight days shows very slight or no alteration excepting at the lines of anastomosis where a moderate thickening occurred, due no doubt to trauma. A segment of external jugular vein similarly engrafted on common carotid artery for twenty-eight days shows a moderate and somewhat irregular thickening of the wall, but the thickening is not nearly so great as in another such experiment previously reported.
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The intima is smooth and glistening but yellowish, particularly in the more thickened areas. The latter are very richly supplied with apparently newly formed blood vessels. Muscle fibers are almost or entirely absent. Elastic fibers are fairly abundant in the middle coats. The remainder of the tissue is more or less hyaline in appearance. The adventitial coat is the most thickened and dense, perivascular fibrosis apparently having occurred.
