Microsurgeons can reconnect arteries to bring blood into the reattached part but veins taking blood from the area often must be left to heal on their own. The leeches suck the blood from the body part until the veins start working. Medicine Quest regales the reader with dozens of such stories about potentially healing chemicals in the venom of snakes, spiders, and cone snails, and the secretions of sponges and sea squirts. Nor are plant medicinals ignored. Frankincense is also a resin from a closely related tree.
Modern experiments support the old wisdom.
These resins are antifungal, anti-inflammatory, relieve pain, kill some bacteria, and more. Silphium, a species of wild fennel, was used by ancient Greeks and Romans as a safe and effective female contraceptive. Plotkin reports that it was then worth more than its weight in silver. Modern studies of common fennel reveal some contraceptive activity, but we'll never know just how truly effective silphium was. The fear that we might lose many, many other cures from nature gives urgency to Plotkin's and others' quest.