20世纪上半叶,美国密西根州比拉镇附近的农场里,农场的主人养了一头公牛,他用铁链把牛锁在了榆树上。健壮的公牛经常拖着重重的铁链围着榆树奔跑。日复一日,铁链在距离地面约3英尺的树干上勒出了一道沟痕。数年之后,铁链已深深地嵌在了树皮中,和树干牢牢地长在了一起。后来有一年,密西根州遭到“荷兰榆树病”的袭击,大片榆树染病枯萎死亡。人们都以为这棵高大、古老的榆树肯定不会幸免。 In the first half of the 20th century, the owner of the farm raised a bull in a farm near Pila town, Michigan, United States, and locked the bull with an iron chain in the elm tree. The sturdy bulls often run around the elms with heavy iron chains. Day after day, the chain leveled a furrow on the trunk about 3 feet above the ground. Years later, the chains were deeply embedded in the bark and grew firmly with the trunk. One year later, Michigan was attacked by “Dutch Elm Disease,” and large-scale elm trees withered and died. People think this tall, ancient elm will certainly not be spared.